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Sample records for fluoride ion selective

  1. Determination of fluoride content in drinking water and tea infusions using fluoride ion selective electrode

    Directory of Open Access Journals (Sweden)

    Rajković Miloš B.

    2007-01-01

    Full Text Available Potentiometric analysis of fluoride content (as F- ion in solutions by using fluoride ion-selective electrode is simple, reliable and cheap. Very small concentrations of fluoride-ions (to 10-6 mol/dm3 can be determined by fluoride selective electrode, with regulation of ion strength of a solution and control of concentration of hydroxide ions and interfering ions of metals. The influence of pH and complexing ions of metals can be successfully regulated by the TISAB solution and by preserving pH value in the range from 5.00 to 7.00. The content of fluorides in the samples can be determined by the method of direct potentiometer, and in the case of very low concentration by standard addition method. In this paper it was analyzed the determination of fluoride ions concentration in bottled mineral waters and water from Belgrade plumbing in two Belgrade districts (Palilula and Novi Beograd and in tea, by using the fluoride selective electrode. It was determined that the content of fluoride ions in bottled mineral water significantly differs from values given on declaration, and that content of fluoride ions varies over a period of time. The content of fluoride ions in water from plumbing in two Belgrade districts at the time of analysis was significantly increased and exceeded values given in Regulation for drinking water quality. The received results from the analysis of fluorides in teas show that fluorides exist in teas in different concentrations. There are also differences between the same kinds of tea, which is noted with mint (Mentha piperitae folium, as a consequence of differences between soils where it was planted. As taking of fluorides, according to World Health Organisation recommendation (WHO, is limited in the range from 2 to 4 mg per day, it is necessary to give the content of fluorides on all products that are used in human consumption.

  2. Determination of the stability constant of Np(V) fluoride complex using a fluoride ion selective electrode

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, R.M.; Rizvi, G.H.; Chaudhuri, N.K.; Patil, S.K. (Bhabha Atomic Research Centre, Bombay (India). Radiochemistry Div.)

    1985-04-01

    Fluoride complexing of Np(V) was studied using fluoride ion selective electrode (F-ISE). Free fluoride ion concentrations in the presence of Np(V) were measured at 0.1 and 0.01M ionic strength. The data were used to calculate the stability constant of the fluoride complex of Np(V) and the values obtained are reported.

  3. Studies on fluoride complexing of hexavalent actinides using a fluoride ion selective electrode

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, R.M.; Chaudhuri, N.K.; Rizvi, G.H.; Patil, S.K.

    1985-08-01

    Complex formation between actinide(VI) and fluoride ions in aqueous solutions was investigated using a fluoride ion selective electrode (F-ISE). As fairly high acidity used to suppress hydrolysis of the actinide(VI) ions, significant liquid junction potentials (Esub(j)) existed in the system. An iterative procedure was developed for computing free hydrogen ion concentration (Hsup(+)) as it could not be measured directly, using data obtained with F-ISE. Esub(j) values were estimated from known (Hsup(+)) and the stability constants of fluoride complexes of actinide(VI) ions were calculated following King and Gallagher's method using a computer program. The stability constants were found to follow the order U(VI) > Np(VI) > Pu(VI). (author). 18 refs.; 3 figs.; 9 tables.

  4. New Inorganic Ion-exchange Material for the Selective Removal of Fluoride from Potable Water Using Ion-selective Electrode

    Directory of Open Access Journals (Sweden)

    Rasheed M.A.Q. Jamhour

    2005-01-01

    Full Text Available An ion-exchange procedure involving the selective retention of fluoride ions from aqueous solutions containing 1, 5, 10, 20 and 50 mg F- L-1 using a new inorganic ion exchanger zirconium(IV oxide-ethanolamine ZrO-EA and its application to fluoride removal from potable water has been described. A column equilibrium studies, batch process and different analytical parameters such as concentration, pH and temperature for the quantitative recoveries of F- ion using ZrO-EA exchanger were investigated and determined by an ion selective electrode. The effect of some other anions that might be present with the analyte was also examined. The column experiments showed a quantitative collection of fluoride at low concentration in water samples with more than 96% recovery.

  5. Development of gold standard ion-selective electrode-based methods for fluoride analysis.

    Science.gov (United States)

    Martínez-Mier, E A; Cury, J A; Heilman, J R; Katz, B P; Levy, S M; Li, Y; Maguire, A; Margineda, J; O'Mullane, D; Phantumvanit, P; Soto-Rojas, A E; Stookey, G K; Villa, A; Wefel, J S; Whelton, H; Whitford, G M; Zero, D T; Zhang, W; Zohouri, V

    2011-01-01

    Currently available techniques for fluoride analysis are not standardized. Therefore, this study was designed to develop standardized methods for analyzing fluoride in biological and nonbiological samples used for dental research. A group of nine laboratories analyzed a set of standardized samples for fluoride concentration using their own methods. The group then reviewed existing analytical techniques for fluoride analysis, identified inconsistencies in the use of these techniques and conducted testing to resolve differences. Based on the results of the testing undertaken to define the best approaches for the analysis, the group developed recommendations for direct and microdiffusion methods using the fluoride ion-selective electrode. Initial results demonstrated that there was no consensus regarding the choice of analytical techniques for different types of samples. Although for several types of samples, the results of the fluoride analyses were similar among some laboratories, greater differences were observed for saliva, food and beverage samples. In spite of these initial differences, precise and true values of fluoride concentration, as well as smaller differences between laboratories, were obtained once the standardized methodologies were used. Intraclass correlation coefficients ranged from 0.90 to 0.93, for the analysis of a certified reference material, using the standardized methodologies. The results of this study demonstrate that the development and use of standardized protocols for F analysis significantly decreased differences among laboratories and resulted in more precise and true values. 2010 S. Karger AG, Basel.

  6. Determination of Boron Trifluoride in Boron Trifluoride Complex by Fluoride Ion Selective Electrode

    Institute of Scientific and Technical Information of China (English)

    郎五可; 张卫江; 唐银; 徐姣; 张雷

    2016-01-01

    A method was proposed to determine boron trifluoride in boron trifluoride complex using fluoride ion selective electrode(ISE). Hydroxide was chosen to mask aluminum for the determination of 0.01—0.1 mol/L of fluoride. The simulation indicated that the permissible aluminum masked at a certain pH value was limited and hardly related to F-concentration and boric acid. It is better to control pH value below 11.5 and the aluminum con-centration within 0.025 mol/L to minimize the interference of hydroxide to the fluoride ISE. The decomposition conditions of boron trifluoride by aluminum chloride were investigated. It is found that the F-detection ratio will approach 1.0 if the Al/F molar ratio is 0.3—0.7 and aluminum concentration is no more than 0.02 mol/L when heated at 80℃ for 10 min. In one word, hydroxide is quite fit to mask aluminum for samples which contain high content of fluoride and aluminum and the BF3 content can be successfully determined by this method.

  7. A simple hydrazine based molecule for selective detection of Fluoride ion in DMSO

    Indian Academy of Sciences (India)

    ADDITI ROY CHOWDHURY; PRIYABRATA BANERJEE

    2017-04-01

    A newly synthesized hydrazine-functionalized Schiff base chemoreceptor [N¹N³−bis(4-cyanobenzylidene) isophthalahydrazide], NBCBIH has been prepared and successfully utilized for selective detection of Fluoride ion. Herein, NH and C=N-like functional units have been incorporated which providebetter colorimetric response compared to systems where such kind of units are absent. On exposure to F⁻, NBCBIH turns from almost colorless to yellow. The recognition is well-supported by UV-Vis, fluorescence and ¹H-NMR in DMSO. The fluorescence quenching is well-explained by photoinduced electron transfer mechanism (PET). The limit of detection of F− with NBCBIH is 0.7 × 10⁻⁴M.

  8. Naphthalenyl appended semicarbazone as ;turn on; fluorescent chemosensor for selective recognition of fluoride ion

    Science.gov (United States)

    Basheer, Sabeel M.; Haribabu, Jebiti; Bhuvanesh, Nattamai S. P.; Karvembu, Ramasamy; Sreekanth, Anandaram

    2017-10-01

    The reaction of 1-isocyanatonaphthalene with hydrazine hydrate in presence of acetone resulted in the formation of napthyl based semicarbazone (1). The compound has been characterized using UV-Visible, FT-IR, NMR, mass spectroscopic and single crystal X-ray diffraction (XRD) tools. The interaction between 1 and fluoride ion has been investigated by means of UV-Visible and fluorescence spectra. The fluoride ion sensing mechanism of 1 has been studied by hybrid density functional theory (DFT) and time dependent DFT (TD-DFT) methods. The added fluoride ion formed intermolecular hydrogen bonds with the protons of N1sbnd H1 and N2sbnd H2 groups of 1 in the ground state. The N1sbnd H1 proton which is closer to naphthalene moiety prefers to bind fluoride anion in the excited state after deprotonation, which lead to excited state proton transfer (ESPT). The fluoride ion sensing process shows a moderate (31.99 kcal/mol) Gibbs free energy. To understand the dynamic features, the transition state (TS) calculation is performed and the change in entropy is found to be -0.6259 kJ/mol, which shows that the sensing process is thermodynamically allowed.

  9. Determination of Fluoride Levels of Sakarya City Drinking Water by Ion-Selective Electrodes and Ion Chromatography

    Directory of Open Access Journals (Sweden)

    Hüseyin Altundağ

    2011-12-01

    Full Text Available Fluoride, next to industrial use of the biological importance of a element. Therefore the levels of floride in the drinking water are important because of public health. In this study, a total 10 samples are taken from 9 different points, which contain drinking water in Sakarya, center and regions of the city (Kampüs, Serdivan, Ozanlar, Camili, Karaman, Erenler1, Erenler2, Cark Caddesi, Hızırtepe and Dortyol. In these samples, determination of flouride was made with ion selective electrode and ion chromatography methods. World Health Organisation (WHO suggests flouride amount in drinking water less than 1,5 mg/L. In drinking water samples which are taken from Sakarya, center and regions of the city avarage flouride values were determined in accordance with standards less than 1,5 mg/L.

  10. Capillary electrophoresis with contactless conductivity detection for the quantification of fluoride in lithium ion battery electrolytes and in ionic liquids-A comparison to the results gained with a fluoride ion-selective electrode.

    Science.gov (United States)

    Pyschik, Marcelina; Klein-Hitpaß, Marcel; Girod, Sabrina; Winter, Martin; Nowak, Sascha

    2017-02-01

    In this study, an optimized method using capillary electrophoresis (CE) with a direct contactless conductivity detector (C(4) D) for a new application field is presented for the quantification of fluoride in common used lithium ion battery (LIB) electrolyte using LiPF6 in organic carbonate solvents and in ionic liquids (ILs) after contacted to Li metal. The method development for finding the right buffer and the suitable CE conditions for the quantification of fluoride was investigated. The results of the concentration of fluoride in different LIB electrolyte samples were compared to the results from the ion-selective electrode (ISE). The relative standard deviations (RSDs) and recovery rates for fluoride were obtained with a very high accuracy in both methods. The results of the fluoride concentration in the LIB electrolytes were in very good agreement for both methods. In addition, the limit of detection (LOD) and limit of quantification (LOQ) values were determined for the CE method. The CE method has been applied also for the quantification of fluoride in ILs. In the fresh IL sample, the concentration of fluoride was under the LOD. Another sample of the IL mixed with Li metal has been investigated as well. It was possible to quantify the fluoride concentration in this sample.

  11. Effect of humic substances aggregation on the determination of fluoride in water using an ion selective electrode.

    Science.gov (United States)

    Shen, Junjie; Gagliardi, Simona; McCoustra, Martin R S; Arrighi, Valeria

    2016-09-01

    The control of drinking water quality is critical in preventing fluorosis. In this study humic substances (HS) are considered as representative of natural organic matter (NOM) in water. We show that when HS aggregate the response of fluoride ion selective electrodes (ISE) may be perturbed. Dynamic light scattering (DLS) results of both synthetic solutions and natural water sample suggest that low pH and high ionic strength induce HS aggregation. In the presence of HS aggregates, fluoride concentration measured by ISE has a reduction up to 19%. A new "open cage" concept has been developed to explain this reversible phenomenon. The interference of HS aggregation on fluoride measurement can be effectively removed by centrifugation pretreatment.

  12. Determination of Fluoride in Toothpaste Using an Ion-Selective Electrode

    Science.gov (United States)

    Light, Truman S.; Cappuccino, Carleton C.

    1975-01-01

    Outlines the theory of chemical potentiometry, describes the experimental procedure for free fluoride determination, and presents sample data of fluoride concentration for various brands of toothpaste. (GS)

  13. Thiourea Based Tweezer Anion Receptors for Selective Sensing of Fluoride Ions

    Institute of Scientific and Technical Information of China (English)

    ZHANG,You-Ming; CAO,Cheng; WEI,Wei; WEI,Tai-Bao

    2007-01-01

    Three 3,3'-di(4-substituted-phenyl)-1,1'-isophthaloylbis(thiourea) compounds were designed as novel neutral anion receptors, and synthesized by simple steps in good yields. The single crystal structure of receptor 1 shows that a solvent molecule was captured by the host molecule through intermolecular hydrogen bonding. Moreover, it was self-assembled as a supramolecular system for the presence of abundant inter- and intramolecular hydrogen bonding and π-π interactions between phenyl groups. Their application as anion receptors has been examined by UV-Vis and 1H NMR spectroscopy, showing that they had a higher selectivity for fluoride than other halides. The host and guest formed a 1∶1 stoichiometry complex through hydrogen bonding interactions in the first step, then following a process of deprotonation in presence of an excess of F- in the solvent of DMF.

  14. Fluorometric selective detection of fluoride ions in aqueous media using Ag doped CdS/ZnS core/shell nanoparticles.

    Science.gov (United States)

    Boxi, Siddhartha Sankar; Paria, Santanu

    2016-01-14

    The presence of fluoride ions in drinking water plays an important role in human health. For that reason, maintaining the optimum concentration of fluoride ions in drinking water is essential, as both low and excess (above the permissible level) concentrations can cause different health problems, such as fluorosis, urolithiasis, kidney failure, cancer, and can even lead to death. So, development of a simple and low cost method for the detection of fluoride ions in water is highly desirable. In this study, a fluorometric method based on Ag-CdS/Ag-ZnS core/shell nanoparticles is developed for fluoride ion detection. The method was tested in aqueous solution at different pH values. The selectivity and sensitivity of the fluorescence probe was checked in the presence of other anions (Cl(-), Br(-), I(-), NO3(-) SO4(2-), HCO3(-), HPO4(2-), CH3COO(-), and H2PO4(-)) and found there is no significant interference of these associated ions. The fluoride ion concentration was varied in the range 190-22 800 μg L(-1) and a lower detection limit was obtained as 99.7 μg L(-1).

  15. Determination of Fluoride in Various Samples and Some Infusions Using a Fluoride Selective Electrode

    OpenAIRE

    TOKALIOĞLU, Şerife; Kartal, Şenol; ŞAHİN, Uğur

    2004-01-01

    The determination of fluoride in some environmental samples was performed using a fluoride ion-selective electrode. Fluoride concentrations were determined in drinking waters (from different provinces, districts and villages in Turkey), fruit juices, bottled water samples, toothpastes and tooth powders, liquors of Turkish coffee, coffee, linden, rose hip, and various brand tea infusions, and dust samples collected from the Erciyes University campus car park. The average fluoride conc...

  16. Ion release from, and fluoride recharge of a composite with a fluoride-containing bioactive glass

    Science.gov (United States)

    Davis, Harry B.; Gwinner, Fernanda; Mitchell, John C.; Ferracane, Jack L.

    2014-01-01

    Objectives Materials that are capable of releasing ions such as calcium and fluoride, that are necessary for remineralization of dentin and enamel, have been the topic of intensive research for many years. The source of calcium has most often been some form of calcium phosphate, and that for fluoride has been one of several metal fluoride or hexafluorophosphate salts. Fluoride-containing bioactive glass (BAG) prepared by the sol-gel method acts as a single source of both calcium and fluoride ions in aqueous solutions. The objective of this investigation was to determine if BAG, when added to a composite formulation, can be used as a single source for calcium and fluoride ion release over an extended time period, and to determine if the BAG-containing composite can be recharged upon exposure to a solution of 5,000 ppm fluoride. Methods BAG 61 (61% Si; 31% Ca; 4% P; 3% F; 1% B) and BAG 81 (81% Si; 11% Ca; 4% P; 3% F; 1% B) were synthesized by the sol gel method. The composite used was composed of 50/50 Bis-GMA/TEGDMA, 0.8% EDMAB, 0.4% CQ, and 0.05% BHT, combined with a mixture of BAG (15%) and strontium glass (85%) to a total filler load of 72% by weight. Disks were prepared, allowed to age for 24 h, abraded, then placed into DI water. Calcium and fluoride release was measured by atomic absorption spectroscopy and fluoride ion selective electrode methods, respectively, after 2, 22, and 222 h. The composite samples were then soaked for 5 min in an aqueous 5,000 ppm fluoride solution, after which calcium and fluoride release was again measured at 2, 22, and 222 h time points. Results Prior to fluoride recharge, release of fluoride ions was similar for the BAG 61 and BAG 81 composites after 2 h, and also similar after 22 h. At the four subsequent time points, one prior to, and three following fluoride recharge, the BAG 81 composite released significantly more fluoride ions (pfluoride, although the BAG 81 composite was recharged more than the BAG 61 composite. The BAG 61

  17. Stabilisation of tetravalent cerium in perchloric acid medium and measurement of the stability constants of its fluoride complexes using ion selective potentiometry.

    Science.gov (United States)

    Sawant, R M; Rastogi, R K; Mahajan, M A; Chaudhuri, N K

    1996-01-01

    The stability constants of the fluoride complexes of cerium(IV) in 1 M (HClO(4), NaClO(4)) medium have been measured potentiometrically using a fluoride ion-selective electrode. Quantitative oxidation of cerium to its tetravalent state and its stabilisation in the perchlorate medium were accomplished by oxidation with AgO followed by quick addition of a known amount of fluoride ion. This procedure ensures stability of the oxidation state and prevents hydrolysis and polymerisation of Ce(IV). Logarithms of the average values of beta(1), beta(2), beta(3) and beta(4) were estimated to be 7.57+/-0.04, 14.50+/-0.03, 20.13+/-0.37 and 24.14+/-0.10 respectively.

  18. Chemometrics-assisted kinetic-potentiometric methods for simultaneous determination of Fe(II), Al(III), and Zr(IV) using a fluoride ion-selective electrode.

    Science.gov (United States)

    Karimi, Mohammad Ali; Ardakani, Mohammad Mazloum; Ardakani, Reza Behjatmanesh; Mashhadizadeh, Mohammad Hossein; Monfared, Mohammad Reza Zand; Tadayon, Maryam

    2010-01-01

    Partial least-squares (PLS) and principal component regression (PCR) were used for the simple, accurate, and simultaneous determination of Fe(III), Al(III), and Zr(IV) using the kinetic data from a novel potentiometric method. The complex forming reaction rate of Fe(III), Al(III), and Zr(IV) with fluoride ions was monitored by a fluoride ion-selective electrode. The experimental data showed the good ability of ion-selective electrodes as detectors, not only for the direct determination of fluoride ion, but also for simultaneous kinetic-potentiometric analysis using the PLS and PCR methods. The methods are based on the differences observed in the complexation rate of fluoride ions. Results have demonstrated that the simultaneous determination of Fe(III), Al(III), and Zr(IV) can be performed in concentration ranges of 0.5-18.5, 0.2-14.0, and 0.4-21.0 microg/mL, respectively. After the application of PLS, the total root mean square error of prediction (RMSEP) was found to be 0.121, 0.122, and 0.129 for the 10-sample experiment of Fe(III), Al(III), and Zr(IV), respectively. For PCR, the RMSEP was found to be 0.156, 0.162, and 0.178 for the 10-sample experiment of Fe(III), Al(III), and Zr(IV), respectively. The effects of certain foreign ions upon the reaction rate were determined for assessing the selectivity of the method. The proposed methods (H-point standard addition, PLS, and PCR) were evaluated using a set of synthetic sample mixtures, and applied for the simultaneous determination of Fe(III), Al(III), and Zr(IV) in water samples.

  19. Fluoride ion release and solubility of fluoride enriched interim cements.

    Science.gov (United States)

    Lewinstein, Israel; Block, Jonathan; Melamed, Guy; Dolev, Eran; Matalon, Shlomo; Ormianer, Zeev

    2014-08-01

    Interim and definitive restorations cemented with interim cements for a prolonged interval are susceptible to bacterial infiltration and caries formation. The purpose of this in vitro study was to evaluate the long-term fluoride release and solubility of aged ZnO-based interim cements enriched separately with 0.4% NaF and SnF2. Four different brands of cements (Tempbond, Tempbond NE, Procem, and Freegenol) were tested for fluoride release and solubility. For every test, 6 disk specimens of each cement with NaF and SnF2, and 6 with no fluoride enrichment (control) were fabricated, for a total of 72 specimens. The disks were incubated in deionized water. Fluoride ion release was recorded at 1, 7, 14, 21, 63, 91, and 182 days. Solubility was calculated as weight percent after 90 days of incubation. The data were analyzed by analysis of variance with repeated measures and the Tukey honestly significant difference post hoc test (Pfluorides released fluoride ions for at least 182 days. Cements mixed with NaF released more fluoride ions than those mixed with SnF2 (P.97), indicating a diffusion-controlled fluoride release. Cement and fluoride types were the main affecting factors in fluoride ion release. The addition of fluorides slightly increased the solubility of the cements. Given their long-term sustained and diffusive controlled release, these fluorides, particularly NaF when mixed with ZnO-based interim cements, may be useful for caries prevention under provisionally cemented restorations. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  20. Fluoride ion encapsulation by Mg[superscript 2+] ions and phosphates in a fluoride riboswitch

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Aiming; Rajashankar, Kanagalaghatta R.; Patel, Dinshaw J. (Cornell); (MSKCC)

    2012-06-26

    Significant advances in our understanding of RNA architecture, folding and recognition have emerged from structure-function studies on riboswitches, non-coding RNAs whose sensing domains bind small ligands and whose adjacent expression platforms contain RNA elements involved in the control of gene regulation. We now report on the ligand-bound structure of the Thermotoga petrophila fluoride riboswitch, which adopts a higher-order RNA architecture stabilized by pseudoknot and long-range reversed Watson-Crick and Hoogsteen A {sm_bullet} U pair formation. The bound fluoride ion is encapsulated within the junctional architecture, anchored in place through direct coordination to three Mg{sup 2+} ions, which in turn are octahedrally coordinated to water molecules and five inwardly pointing backbone phosphates. Our structure of the fluoride riboswitch in the bound state shows how RNA can form a binding pocket selective for fluoride, while discriminating against larger halide ions. The T. petrophila fluoride riboswitch probably functions in gene regulation through a transcription termination mechanism.

  1. Fluoride ion encapsulation by Mg2+ ions and phosphates in a fluoride riboswitch.

    Science.gov (United States)

    Ren, Aiming; Rajashankar, Kanagalaghatta R; Patel, Dinshaw J

    2012-05-13

    Significant advances in our understanding of RNA architecture, folding and recognition have emerged from structure-function studies on riboswitches, non-coding RNAs whose sensing domains bind small ligands and whose adjacent expression platforms contain RNA elements involved in the control of gene regulation. We now report on the ligand-bound structure of the Thermotoga petrophila fluoride riboswitch, which adopts a higher-order RNA architecture stabilized by pseudoknot and long-range reversed Watson-Crick and Hoogsteen A•U pair formation. The bound fluoride ion is encapsulated within the junctional architecture, anchored in place through direct coordination to three Mg(2+) ions, which in turn are octahedrally coordinated to water molecules and five inwardly pointing backbone phosphates. Our structure of the fluoride riboswitch in the bound state shows how RNA can form a binding pocket selective for fluoride, while discriminating against larger halide ions. The T. petrophila fluoride riboswitch probably functions in gene regulation through a transcription termination mechanism.

  2. 离子选择性电极法测定牙膏中微量的氟%Determination of Fluoride with Ion-selective Electrode in Toothpaste

    Institute of Scientific and Technical Information of China (English)

    邱小香

    2011-01-01

    A new method for determination of fluoride ion was devel oped. Using fluoride ion-selective electrode , adding TISAB buffer control conditions, determined the content of F. It is resultsed that method detection range was 1.0 ×10-1 ~1.0 ×10-6 mol/L, recovery, 98.91 %. It is conclused it is simple, reliable, and worthy of promotion.%测定牙膏中氟离子的含量,使用氟离子选择性电极.通过加入TISAB缓冲溶液控制测定条件,利用电位分析法,完成对牙膏中氟离子的测定.结果:回收率为98.91%,检出限为1.0×10-1-1.0×10-6mol/L.说明操作简便,方法可靠,准确度高,检出限低.值得推广.

  3. Microscale adaptation of the potentiometric method with ion-selective electrode for the quantification of fluoride; Adaptacion a microescala del metodo potenciometrico con electrodo ion selectivo para la cuantificacion de fluoruro

    Energy Technology Data Exchange (ETDEWEB)

    Guevara Ruiz, Paulina; Ortiz Perez, Maria Deogracias [Laboratorio de Bioquimica, Facultad de de Medicina, Universidad Autonoma de San Luis Potosi, San Luis Potosi, San Luis Potosi, (Mexico)]. E-mail: mdortiz@uaslp.mx

    2009-05-15

    Similarly to other countries, ground water from Mexico is naturally polluted by fluoride. The main effects of fluoride at typical ground water concentrations are dental fluorosis, neurological deficits and reproductive disorders. In order to verify that the fluoride concentration is within the allowed guideline in Mexico (NOM 127 and 201), it is important to monitor fluoride levels in water and commercial beverages. The aim of this work is to develop a modification of the standard potentiometric method for fluoride determination in water, in order to reduce costs and amount of potentially toxic waste substances. Both methods were validated, the standard potentiometric method with the ion selective electrode and the microscale modification proposed in this paper. The methods were compared using statistic tests and graphics, followed by the comparison of 125 samples of commercial bottled water sold in the city of San Luis Potosi. Optimal results were obtained for the validation of both methods, and the microscale modification showed statistically identical results to those obtained with the standard method in all samples of bottled water. The microscale modification is a good alternative for fluoride assessment in water and beverages, and it represents a 95 % reduction of costs and chemical waste. [Spanish] En varios paises, incluido Mexico se presenta una contaminacion natural con fluoruro en agua subterranea; los principales efectos en la salud observados en poblacion expuesta a concentraciones mayores al valor permisible (que en Mexico es de 1.5 mg/L) son la fluorosis dental y esqueletica, asi como dano reproductivo y neurologico. En varios estados de la republica Mexicana, este problema es aun desconocido, de ahi la necesidad de evaluar las concentraciones de fluoruro en agua de consumo en varias comunidades. Asi, el objetivo de este trabajo es desarrollar un metodo a microescala para la determinacion de fluoruro en agua, que al reducir la cantidad de reactivo y

  4. Fluorine in drinking water and urine in the urban and rural areas of northwestern China―Its determination by a fluoride ion selective electrode

    Institute of Scientific and Technical Information of China (English)

    WANG Binbin; ZHENG Baoshan; LIAN Weijuan; YANG Lan; HUANG Ruizhe; RUAN Jianping

    2009-01-01

    In this study, the author determined fluorine in drinking water and urine of residents who are divided into four age groups (5, 12, 35-44, 65-74 aged), living in Huangling City, Shaanxi Province and at 6 villages of Qin'an County, Gansu Province, P.R.China. Some residents are living in fluorine exposure areas. A total of 929 residents (463 females and 466 males) involved in the study were selected from 7 tap water systems. Drinking water samples were collected from each area and analyzed using the fluoride ion-selective method. No positive correlation relationship was found between fluorine concentrations in urine and those in drinking water in the area where the fluorine concentrations of drinking water are within the range of 1-2 mg/L. The fluorine absorbed by resistents of different ages is different in amount. With the same concentrations of fluorine in drinking water, more fluorine would be absorbed by young residents than old residents. No difference can be seen in absorption amount of fluorine among different genders.

  5. Effect of fluoride ion on the stability of DNA hairpin

    Science.gov (United States)

    Liu, Chao; Zhai, Weili; Gong, Hongling; Liu, Yanhui; Chen, Hu

    2017-06-01

    Fluoride prevents tooth decay as an additive in oral hygiene products, while high dose intake of fluoride from contaminated drinking water leads to fluorosis. Here we studied the effect of fluoride ion on the stability of DNA double helix using magnetic tweezers. The equilibrium critical force decreases with increasing concentration of fluoride in the range from 1 mM to 100 mM. Our results give the first quantitative measurement of DNA stability in the presence of fluoride ion, which might disturb DNA-related biological processes to cause fluorosis.

  6. Chemically modified field effect transistors with nitrite or fluoride selectivity

    NARCIS (Netherlands)

    Antonisse, Martijn M.G.; Snellink-Ruël, Bianca H.M.; Engbersen, Johan F.J.; Reinhoudt, David N.

    1998-01-01

    Polysiloxanes with different types of polar substituents are excellent membrane materials for nitrite and fluoride selective chemically modified field effect transistors (CHEMFETs). Nitrite selectivity has been introduced by incorporation of a cobalt porphyrin into the membrane; fluoride selectivity

  7. Chemically modified field effect transistors with nitrite or fluoride selectivity

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Ruel, Bianca H.M.; Engbersen, Johannes F.J.; Reinhoudt, David

    1998-01-01

    Polysiloxanes with different types of polar substituents are excellent membrane materials for nitrite and fluoride selective chemically modified field effect transistors (CHEMFETs). Nitrite selectivity has been introduced by incorporation of a cobalt porphyrin into the membrane; fluoride selectivity

  8. Adsorption of Fluoride Ion by Inorganic Cerium Based Adsorbent

    Institute of Scientific and Technical Information of China (English)

    Jiao Zhongzhi(焦中志); Chen Zhonglin; Yang Min; Zhang Yu; Li Guibai

    2004-01-01

    Excess of fluoride in drinking water is harmful to human health, the concentration of F- ions must be maintained in the range of 0.5 to 1.5 mg/L. An inorganic cerium based adsorbent (CTA) is developed on the basis of research of adsorption of fluoride on cerium oxide hydrate. Some adsorption of fluoride by CTA adsorbent experiments were carried out, and results showed that CTA adsorbent has a quick adsorption speed and a large adsorption capacity. Adsorption follows Freundlich isotherm, and low pH value helps fluoride removal. Some physical-chemical characteristics of CTA adsorbent were experimented, fluoride removal mechanism was explored, and results showed that hydroxyl group of CTA adsorbent played an important role in the fluoride removal.

  9. A selective detection of fluoride ions in DMSO by fluorescent and colorimetry competition assays based on 4-bromo-2,6-bis-(hydroxymethyl)phenol

    Institute of Scientific and Technical Information of China (English)

    Hossein Tavallali; Gohar Deilamy-Rad; Mahboobe Tabandeh

    2011-01-01

    A novel and very simple colorimetric and fluorometric method for selectively sensing F-was proposed based on 4-bromo-2,6-bis(hydroxymethyl)phenol (BBHMP), which is a simple and available phenolic receptor the absence of any special chromophoric function and with over wide range of anions (Cl-, Br-, I-, AcO-, HSO4-, NO3-and BzO-) in DMSO media. The colorimetric method is described for naked-eye detection of F~ in the presence of the BBHMP. The BBHMP was found to show selective and sensitive fluorescence quenching response toward fluoride over than Cl-, Br-, I-, AcO-, HSO4-, NO3-and BzO-.

  10. Synthesis and Anion Recognition of Novel Molecular Tweezer Receptors Based on Carbonyl Thiosemicarbazide for Fluoride Ions

    Institute of Scientific and Technical Information of China (English)

    WEI,Wei; ZHANG,You-Ming; WEI,Tai-Bao

    2008-01-01

    Three title compounds have been designed and synthesized in high yields as novel anion receptors, which show a higher selectivity for F- than other halide ions. The binding properties for fluoride ions of the receptors have been examined by UV-Vis and 1H NMR spectroscopy, indicating that a 1 : 1 stoichiometry complex is formed between the receptors and fluoride ions through hydrogen bonding interactions in DMSO solution. In addition, because these receptors have more binding points, they have better binding properties for anions than the molecular tweezer receptors based on thiourea we reported last time.

  11. Toxic fluoride gas emissions from lithium-ion battery fires.

    Science.gov (United States)

    Larsson, Fredrik; Andersson, Petra; Blomqvist, Per; Mellander, Bengt-Erik

    2017-08-30

    Lithium-ion battery fires generate intense heat and considerable amounts of gas and smoke. Although the emission of toxic gases can be a larger threat than the heat, the knowledge of such emissions is limited. This paper presents quantitative measurements of heat release and fluoride gas emissions during battery fires for seven different types of commercial lithium-ion batteries. The results have been validated using two independent measurement techniques and show that large amounts of hydrogen fluoride (HF) may be generated, ranging between 20 and 200 mg/Wh of nominal battery energy capacity. In addition, 15-22 mg/Wh of another potentially toxic gas, phosphoryl fluoride (POF3), was measured in some of the fire tests. Gas emissions when using water mist as extinguishing agent were also investigated. Fluoride gas emission can pose a serious toxic threat and the results are crucial findings for risk assessment and management, especially for large Li-ion battery packs.

  12. Ion release from calcium and fluoride containing dental varnishes.

    Science.gov (United States)

    Cochrane, N J; Shen, P; Yuan, Y; Reynolds, E C

    2014-03-01

    A range of dental varnishes have been commercialized recently that contain calcium and inorganic phosphate in addition to fluoride. The aim of this study was to analyse the fluoride, calcium and inorganic phosphate ion release from: (1) MI Varnish containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP); (2) Clinpro White containing functionalized tricalcium phosphate (fTCP); (3) Enamel Pro containing amorphous calcium phosphate; (4) Bifluorid 5 containing calcium fluoride; and (5) Duraphat (no added calcium control). The varnishes were applied to a standardized surface area of polyvinyl chloride (n = 7 per group) and immersed in 25 g of distilled deionized water which was changed at 1, 4, 24, 72 and 168 hours. The ion release was determined by ion chromatography and expressed as μmol (cumulative) per gram of varnish. All varnishes released measurable fluoride and calcium, however only MI Varnish and Enamel Pro released significant levels of inorganic phosphate. At 24 hours the order of cumulative fluoride release was: 1>3>4>2=5 with 1 significantly higher (p 4>3>2=5 with 1 significantly higher (p fluoride ions. © 2014 Australian Dental Association.

  13. Quantitative measure for the "nakedness" of fluoride ion sources.

    Science.gov (United States)

    Christe, Karl O; Jenkins, H Donald Brooke

    2003-08-01

    A quantitative measure for the donor strength or "nakedness" of fluoride ion donors is presented. It is based on the free energy change associated with the transfer of a fluoride ion from the donor to a given acceptor molecule. Born-Haber cycle calculations were used to calculate both the free energy and the enthalpy change for this process. The enthalpy change is given by the sum of the fluoride ion affinity of the acceptor (as defined in strict thermodynamic convention) and the lattice energy difference (DeltaU(POT)) between the fluoride ion donor and the salt formed with the acceptor. Because, for a given acceptor, the fluoride affinity has a constant value, the relative enthalpy (and also the corresponding free energy) changes are governed exclusively by the lattice energy differences. In this study, BF(3), PF(5), AsF(5), and SbF(5) were used as the acceptors, and the following seven fluoride ion donors were evaluated: CsF, N(CH(3))(4)F (TMAF), N-methylurotropinium fluoride (MUF), hexamethylguanidinium fluoride (HMGF), hexamethylpiperidinium fluoride (HMPF), N,N,N-trimethyl-1-adamantylammonium fluoride (TMAAF), and hexakis(dimethylamino)phosphazenium fluoride (HDMAPF). Smooth relationships between the enthalpy changes and the molar volumes of the donor cations were found which asymptotically approach constant values for infinitely large cations. Whereas CsF is a relatively poor F(-) donor [(U(POT)(CsF) - U(POT)(CsSbF(6))) = 213 kJ mol(-)(1)], when compared to N(CH(3))(4)F [(U(POT)(TMAF) - U(POT)(TMASbF(6))) = 69 kJ mol(-)(1)], a 4 times larger cation (phosphazenium salt) and an infinitely large cation are required to decrease DeltaU(POT) to 17 and 0 kJ mol(-)(1), respectively. These results clearly demonstrate that very little is gained by increasing the cation size past a certain level and that secondary factors, such as chemical and physical properties, become overriding considerations.

  14. Solid electrolytes for fluoride ion batteries: ionic conductivity in polycrystalline tysonite-type fluorides.

    Science.gov (United States)

    Rongeat, Carine; Reddy, M Anji; Witter, Raiker; Fichtner, Maximilian

    2014-02-12

    Batteries based on a fluoride shuttle (fluoride ion battery, FIB) can theoretically provide high energy densities and can thus be considered as an interesting alternative to Li-ion batteries. Large improvements are still needed regarding their actual performance, in particular for the ionic conductivity of the solid electrolyte. At the current state of the art, two types of fluoride families can be considered for electrolyte applications: alkaline-earth fluorides having a fluorite-type structure and rare-earth fluorides having a tysonite-type structure. As regard to the latter, high ionic conductivities have been reported for doped LaF3 single crystals. However, polycrystalline materials would be easier to implement in a FIB due to practical reasons in the cell manufacturing. Hence, we have analyzed in detail the ionic conductivity of La(1-y)Ba(y)F(3-y) (0 ≤ y ≤ 0.15) solid solutions prepared by ball milling. The combination of DC and AC conductivity analyses provides a better understanding of the conduction mechanism in tysonite-type fluorides with a blocking effect of the grain boundaries. Heat treatment of the electrolyte material was performed and leads to an improvement of the ionic conductivity. This confirms the detrimental effect of grain boundaries and opens new route for the development of solid electrolytes for FIB with high ionic conductivities.

  15. Removal of fluoride ion by bone char produced from animal biomass.

    Science.gov (United States)

    Kawasaki, Naohito; Ogata, Fumihiko; Tominaga, Hisato; Yamaguchi, Isao

    2009-01-01

    Bone char (BC) was prepared by carbonizing four types of animal biomass, and the adsorption of fluoride ions and elution of phosphate ions were investigated. It was found that the BC yield decreased as carbonization temperature increased, and that carbonization temperature had no significant effect on surface pH, base or acid consumptions. Fluoride ion adsorption was increased in BC produced at a low carbonization temperature. The adsorption mechanism of fluoride ion on BCs might be monolayer adsorption. BC can potentially be used to remove fluoride ions in drinking water. However, it was found that phosphate ions from BC are eluted due to adsorption of fluoride ions, and that ingestion of large amounts of phosphate ions inhibits reabsorption of calcium in the human body. Thus there is a need to study the elution behavior of phosphate ions. The adsorption mechanisms of fluoride ions onto BC would be a physical adsorption onto BC and phosphate ion in BC is exchanged to fluoride ion.

  16. Novel azo dye-based color chemosensors for fluoride ions.

    Science.gov (United States)

    Cho, Eun Jin; Lee, Yongjun; Bae, Hyeun-Jong; Lee, Young Ju

    2015-01-01

    Two novel fluoride (F(-)) sensors based on an azo dye (solvent yellow 4) were designed and synthesized. The chemosensors exhibited selectivity and high sensitivity towards F(-) over other anions such as Cl(-), Br(-), I(-), CH3COO(-), C6H5COO(-), and H2PO4(-), as noted by the naked eye and UV-vis spectral changes in DMSO/CH3CN (1:9, v/v). An obvious change in the color of the sensor solution from pale yellow to pink occurred after the addition of F(-), while the addition of other anions did not cause any change in color. These results imply that the two sensors are viable, portable chemosensors for the detection of F(-) ions in various biological and environmental fields. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Ratiometric fluorescence signalling of fluoride ions by an amidophthalimide derivative

    Indian Academy of Sciences (India)

    Moloy Sarkar; Raghavendra Yellampalli; Bhaswati Bhattacharya; Ravi Kumar Kanaparthi; Anunay Samanta

    2007-03-01

    Fluorescence behaviour of 4-benzoylamido-N-methylphthalimide (1), designed and developed for selective detection of fluoride ions, is reported. 1 displays F--induced colour change that allows its detection with the naked eye. The F- specificity of the sensor system is evident from the fact that unlike F-, other halides do not affect the absorption characteristics of 1. Apart from the colorimetric response, the fluorescence output of 1 is also modulated by F- in a manner that permits ratiometric fluorescence signalling of F- as well. It is found that the system can detect F- in the concentration range of 10- 60 M. The results of the experiments and theoretical calculations unambiguously suggest that the changes of the electronic absorption and fluorescence behaviour of 1, which have been exploited for signalling purpose, are due to F--induced deprotonation of the 4-amido moiety of the sensor system.

  18. A highly sensitive colorimetric and ratiometric sensor for fluoride ion

    Institute of Scientific and Technical Information of China (English)

    Zhao Wu Xu; Jin Tang; He Tian

    2008-01-01

    A new benzoimidazole-naphthalimide derivative 4 was synthesized and its photophysical properties were studied.This compound showed highly selectively and sensitive colorimetric and ratiometric sensing ability for fluoride anion.

  19. Removal of fluoride ions from aqueous solution by waste mud

    Energy Technology Data Exchange (ETDEWEB)

    Kemer, Baris; Ozdes, Duygu; Gundogdu, Ali; Bulut, Volkan N.; Duran, Celal [Karadeniz Technical University, Faculty of Arts and Sciences, Department of Chemistry, 61080 Trabzon (Turkey); Soylak, Mustafa, E-mail: soylak@erciyes.edu.tr [Erciyes University, Faculty of Arts and Sciences, Department of Chemistry, 38039 Kayseri (Turkey)

    2009-09-15

    The present study was carried out to assess the ability of original waste mud (o-WM) and different types of activated waste mud which are acid-activated (a-WM) and precipitated waste mud (p-WM), in order to remove excess of fluoride from aqueous solution by using batch technique. The p-WM exhibited greater performance than the others. Adsorption studies were conducted as a function of pH, contact time, initial fluoride concentration, adsorbent concentration, temperature, etc. Studies were also performed to understand the effect of some co-existing ions present in aqueous solutions. Adsorption process was found to be almost independent of pH for all types of waste mud. Among the kinetic models tested for p-WM, pseudo-second-order model fitted the kinetic data well with a perfect correlation coefficient value of 1.00. It was found that the adequate time for the adsorption equilibrium of fluoride was only 1 h. Thermodynamic parameters including the Gibbs free energy ({Delta}G{sup o}), enthalpy ({Delta}H{sup o}), and entropy ({Delta}S{sup o}) revealed that adsorption of fluoride ions on the p-WM was feasible, spontaneous and endothermic in the temperature range of 0-40 deg. C. Experimental data showed a good fit with the Langmuir and Freundlich adsorption isotherm models. Results of this study demonstrated the effectiveness and feasibility of WM for removal of fluoride ions from aqueous solution.

  20. Removal of fluoride ions from aqueous solution by waste mud.

    Science.gov (United States)

    Kemer, Baris; Ozdes, Duygu; Gundogdu, Ali; Bulut, Volkan N; Duran, Celal; Soylak, Mustafa

    2009-09-15

    The present study was carried out to assess the ability of original waste mud (o-WM) and different types of activated waste mud which are acid-activated (a-WM) and precipitated waste mud (p-WM), in order to remove excess of fluoride from aqueous solution by using batch technique. The p-WM exhibited greater performance than the others. Adsorption studies were conducted as a function of pH, contact time, initial fluoride concentration, adsorbent concentration, temperature, etc. Studies were also performed to understand the effect of some co-existing ions present in aqueous solutions. Adsorption process was found to be almost independent of pH for all types of waste mud. Among the kinetic models tested for p-WM, pseudo-second-order model fitted the kinetic data well with a perfect correlation coefficient value of 1.00. It was found that the adequate time for the adsorption equilibrium of fluoride was only 1h. Thermodynamic parameters including the Gibbs free energy (DeltaG degrees ), enthalpy (DeltaH degrees ), and entropy (DeltaS degrees ) revealed that adsorption of fluoride ions on the p-WM was feasible, spontaneous and endothermic in the temperature range of 0-40 degrees C. Experimental data showed a good fit with the Langmuir and Freundlich adsorption isotherm models. Results of this study demonstrated the effectiveness and feasibility of WM for removal of fluoride ions from aqueous solution.

  1. Fluoride ion promoted deprotection and transesterification in nucleotide triesters.

    Science.gov (United States)

    Ogilvie, K K; Beaucage, S L

    1979-10-10

    Tetrabutylammonium fluoride will remove phenyl, trichloroethyl and cyanoethyl groups from nucleotides. In addition to the desired nucleotide products other results including chain cleavage, phosphofluoridates and cyanoethylated thymidine units may be obtained depending on the conditions used. Fluoride ion has been used to successfully exchange phenyl and trichloroethyl groups for methyl, ethyl and butyl groups in nucleotide triesters. This represents a rapid high yield route to a variety of phosphate esters. The synthesis of a novel nucleotide analogue in which two chains are bridged through their phosphates is described.

  2. Eletrodo íon-seletivo para determinação potenciométrica de alumínio(III em meio de fluoreto Ion-selective electrode for potentiometric determination of aluminium(III in fluoride medium

    Directory of Open Access Journals (Sweden)

    Evandro Piccin

    2004-12-01

    Full Text Available The construction and analytical evaluation of a coated graphite Al(III ion-selective electrode, based on the ionic pair formed between the Al(Fn3-n anion and tricaprylylmethylammonium cation (Aliquat 336S incorporated on a poly(vinylchloride (PVC matrix membrane are described. A thin membrane film of this ionic pair and dibutylphthalate (DBPh in PVC was deposited directly on a cylindric graphite rod (2 cm length x 0.5 cm diameter attached to the end of a glass tube using epoxy resin. The membrane solution was prepared by dissolving 40% (m/m of PVC in 10 mL of tetrahydrofuran following addition of 45% (m/m of DBPh and 15% (m/m of the ionic pair. The effect of membrane composition, fluoride concentration, and several concomitants as potential interferences on the electrode response were investigated. The aluminium(III ion-selective electrode showed a linear response ranging from 1.4 x 10-4 to 1.0 x 10-2 mol L-1, a detection limit of 4.0 x 10-5 mol L-1, aslope of -54.3±0.2mV dec-1 and a lifetime of more than 1 year (over 3000 determinations for each membrane. The slope indicates that the ion-selective electrode responds preferentially to the Al(F4- species. Application of this electrode for the aluminium(III determination in stomach anti-acid samples is reported.

  3. Investigating the Intercalation Chemistry of Alkali Ions in Fluoride Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Tanghong; Chen, Wei; Cheng, Lei; Bayliss, Ryan D.; Lin, Feng; Plews, Michael R.; Nordlund, Dennis; Doeff, Marca M.; Persson, Kristin A.; Cabana, Jordi

    2017-02-07

    Reversible intercalation reactions provide the basis for modern battery electrodes. Despite decades of exploration of electrode materials, the potential for materials in the nonoxide chemical space with regards to intercalation chemistry is vast and rather untested. Transition metal fluorides stand out as an obvious target. To this end, we report herein a new family of iron fluoride-based perovskite cathode materials AxK1–xFeF3 (A = Li, Na). By starting with KFeF3, approximately 75% of K+ ions were subsequently replaced by Li+ and Na+ through electrochemical means. X-ray diffraction and Fe X-ray absorption spectroscopy confirmed the existence of intercalation of alkali metal ions in the perovskite structure, which is associated with the Fe2+/3+ redox couple. A computational study by density functional theory showed agreement with the structural and electrochemical data obtained experimentally, which suggested the possibility of fluoride-based materials as potential intercalation electrodes. This study increases our understanding of the intercalation chemistry of ternary fluorides, which could inform efforts toward the exploration of new electrode materials.

  4. Electrodeposited apatite coating for solid-phase microextraction and sensitive indirect voltammetric determination of fluoride ions.

    Science.gov (United States)

    Mao, Yuehong; Chen, Yufei; Chu, Lin; Zhang, Xiaoli

    2013-10-15

    Electrodeposition was used to prepare a new solid phase microextraction (SPME) coatings. Two apatite SPME coatings, dicalcium phosphate dihydrate (DCPD or brushite) and hydroxyapatite (HAP) were validly and homogeneously one-step electrodeposited on glassy carbon electrode (GCE) under different conditions. The coatings were characterized by XRD, FTIR, SEM, CV and EIS. The apatite SPME coatings showed excellent and selective adsorbability to fluoride ions. A novel indirect voltammetric strategy for sensitive detection of fluoride was proposed using K3Fe(CN)6 as indicating probe. The detection principle of fluoride ions was based on the increment of steric hindrance after fluoride adsorption, which resulting in the decrease of the amperometric signal to Fe(CN)6(3-). The liner ranges were 0.5-20.0 μmol/L for n-DCPD/GCE with the limit of detection of 0.14 μmol/L and 0.1-50.0 μmol/L for n-HAP/GCE with the limit of detection of 0.069 μmol/L, respectively. The developed method was applied to the analysis of water samples (lake, spring and tap water) and the recovery values were found to be in the range of 90-106%.

  5. Selective separation of phosphate and fluoride from semiconductor wastewater.

    Science.gov (United States)

    Warmadewanthi, B; Liu, J C

    2009-01-01

    Hydrofluoric acid (HF) and phosphoric acid (H(3)PO(4)) are widely used in semiconductor industry for etching and rinsing purposes. Consequently, significant amount of wastewater containing phosphate and fluoride is generated. Selective separation of phosphate and fluoride from the semiconductor wastewater, containing 936 mg/L of fluoride, 118 mg/L of phosphate, 640 mg/L of sulfate, and 26.7 mg/L of ammonia, was studied. Chemical precipitation and flotation reactions were utilized in the two-stage treatment processes. The first-stage reaction involved the addition of magnesium chloride (MgCl(2)) to induce selective precipitation of magnesium phosphate. The optimal condition was pH 10 and molar ratio, [Mg(2 + )]/[(PO(4) (3-))], of 3:1, and 66.2% of phosphate was removed and recovered as bobierrite (Mg(3)(PO(4))(2).8H(2)O). No reaction was found between MgCl(2) and fluoride. Calcium chloride (CaCl(2)) was used in the second-stage reaction to induce precipitation of calcium fluoride and calcium phosphate. The optimum molar ratio, [Ca(2 + )]/[F(-)], was 0.7 at pH 10, and residual fluoride concentration of 10.7 mg/L and phosphate concentration of lower than 0.5 mg/L was obtained. Thermodynamic equilibrium was modeled with PHREEQC and compared with experimental results. Sodium dodecylsulfate (SDS) was an effective collector for subsequent solid-liquid removal via dispersed air flotation (DiAF). The study demonstrated that phosphate can be selectively recovered from the wastewater. Potential benefits include recovery of phosphate for reuse, lower required dosage of calcium for fluoride removal, and less amount of CaF(2) sludge.

  6. 氟离子选择电极法测定砖茶中氟含量的稳定性研究%Stability of fluoride ion selective electrode method to detect fluorine content in brick tea

    Institute of Scientific and Technical Information of China (English)

    李戎娟; 刘东娜; 李俊; 魏晓惠; 杜晓

    2013-01-01

    Objective To explore the stability of fluoride ion selective electrode method to detect fluorine content in brick tea, and provide theoretical data for its calibration. Methods Samples were extracted by boiling water, using TISAB buffer solution to eliminate the effect of interfering ions and acidity, and then measured by fluoride ion selective electrode. Results The factors had an obvious influence on the content of fluorine in brick tea, such as the buffer ionic strength, sample consumption, electrode, stirring speed, and filtra-tion condition. The detection of fluorine content in brick tea by using 120 g/L (TISAB-2) sodium citrate buffer solution were more accurate, and there was no significant difference in fluorine content between 120 g/L (TISAB-2) and 110 g/L (TISAB-GB) sodium citrate buffer solution. The fluorine content in 0.25 g samples reached the high value of 490.73±6.36 mg/kg, and this fluorine content was more accurate. The determination results showed that the new electrode was more stable than that by older electrode, the medium and high stir-ring speed were more stable and reliable than low stirring speed, and the qualitative filtration was much better than no filtration and quantitative filtration. Conclusion Under the optimum conditions, this method is accu-rate and stable, and it is suitable for the determination of fluorine content in brick tea.%  目的探讨氟离子选择电极法测定砖茶氟含量的稳定性,为该方法的校准提供理论数据。方法样品经沸水提取、缓冲溶液消除离子及酸度的干扰后,采用氟离子选择电极法测定砖茶试样中氟含量。结果缓冲溶液(TISAB)离子强度、试样用量、电极、搅拌速度、过滤条件等实验因素对样品氟含量测定结果影响极显著,其中以含柠檬酸钠120 g/L(TISAB-2)的缓冲液测定结果较准确,且与国标法(TISAB-GB)测定结果差异不显著;试样用量为0.25 g时,样品中氟含量值较高,为490.73±6.36 mg

  7. Fluoride

    Science.gov (United States)

    Fluoride is used to prevent tooth decay. It is taken up by teeth and helps to strengthen ... and block the cavity-forming action of bacteria. Fluoride usually is prescribed for children and adults whose ...

  8. Nanocrystalline rare earth fluorides doped with Pr3+ions

    Institute of Scientific and Technical Information of China (English)

    Marcin Runowski; Stefan Lis

    2016-01-01

    Praseodymium(III) doped CeF3, CeF3:Gd, LaF3, GdF3 and YF3 inorganic fluorides were precipitated in an aqueous, sur-factant-free solution, using NH4F as a source of fluoride ions. The as-prepared products were subjected to a hydrothermal treatment, which led to the formation of crystalline nanoluminophores, composed of spherical (≈30 nm) and elongated (≈40–200 nm) nanos-tructures. Due to the presence of Pr3+ions, the synthesized nanomaterials showed yellow luminescence under a blue light irradiation. The nanoluminophore based on the YF3 host revealed the most promising spectroscopic properties, i.e., bright and intensive emission, hence it was investigated in detail. The photophysical properties of the nanomaterials obtained were studied by powder X-ray diffrac-tion (XRD), transmission electron microscopy (TEM) and spectrofluorometry, i.e., measurements of excitation/emission spectra and luminescence decay curves.

  9. Ion-selective electrodes

    CERN Document Server

    Mikhelson, Konstantin N

    2013-01-01

    Ion-selective electrodes (ISEs) have a wide range of applications in clinical, environmental, food and pharmaceutical analysis as well as further uses in chemistry and life sciences. Based on his profound experience as a researcher in ISEs and a course instructor, the author summarizes current knowledge for advanced teaching and training purposes with a particular focus on ionophore-based ISEs. Coverage includes the basics of measuring with ISEs, essential membrane potential theory and a comprehensive overview of the various classes of ion-selective electrodes. The principles of constructing I

  10. Ion-selective electrode reviews

    CERN Document Server

    Thomas, J D R

    1983-01-01

    Ion-Selective Electrode Reviews, Volume 5 is a collection of articles that covers ion-speciation. The book aims to present the advancements of the range and capabilities of selective ion-sensors. The topics covered in the selection are neutral carrier based ion-selective electrodes; reference electrodes and liquid junction effects in ion-selective electrode potentiometry; ion transfer across water/organic phase boundaries and analytical; and carbon substrate ion-selective electrodes. The text will be of great use to chemists and chemical engineers.

  11. Fluorescent naphthalene-based benzene tripod for selective recognition of fluoride in physiological condition

    Indian Academy of Sciences (India)

    Barun kumar Datta; Chirantan Kar; Gopal Das

    2015-02-01

    Aluminium complex of a naphthalene-based benzene tripod ligand system has been reported for the selective recognition of fluoride in aqueous medium in physiological condition. The ligand can selectively recognize Al3+ through enhancement in the fluorescence intensity and this in situ formed aluminium complex recognizes fluoride through quenching of fluorescence. The receptor system detects fluoride in nanomolar range. The sensing property was extended for practical utility to sense fluoride in tap water, pond water and river water.

  12. Highly sensitive and selective fluoride detection in water through fluorophore release from a metal-organic framework.

    Science.gov (United States)

    Hinterholzinger, Florian M; Rühle, Bastian; Wuttke, Stefan; Karaghiosoff, Konstantin; Bein, Thomas

    2013-01-01

    The detection, differentiation and visualization of compounds such as gases, liquids or ions are key challenges for the design of selective optical chemosensors. Optical chemical sensors employ a transduction mechanism that converts a specific analyte recognition event into an optical signal. Here we report a novel concept for fluoride ion sensing where a porous crystalline framework serves as a host for a fluorescent reporter molecule. The detection is based on the decomposition of the host scaffold which induces the release of the fluorescent dye molecule. Specifically, the hybrid composite of the metal-organic framework NH2-MIL-101(Al) and fluorescein acting as reporter shows an exceptional turn-on fluorescence in aqueous fluoride-containing solutions. Using this novel strategy, the optical detection of fluoride is extremely sensitive and highly selective in the presence of many other anions.

  13. Ion-selective electrode reviews

    CERN Document Server

    Thomas, J D R

    1985-01-01

    Ion-Selective Electrode Reviews, Volume 7 is a collection of papers that covers the applications of electrochemical sensors, along with the versatility of ion-selective electrodes. The coverage of the text includes solid contact in membrane ion-selective electrodes; immobilized enzyme probes for determining inhibitors; potentiometric titrations based on ion-pair formation; and application of ion-selective electrodes in soil science, kinetics, and kinetic analysis. The text will be of great use to chemists and chemical engineers.

  14. Removal of fluoride ion from aqueous solution by a cerium-poly(hydroxamic acid) resin complex.

    Science.gov (United States)

    Haron, M J; Yunus, W M

    2001-05-01

    A cerium-loaded poly(hydroxamic acid) chelating ion exchanger was used for fluoride ion removal from aqueous solution. The resin was effective in decreasing the fluoride concentration from 5 mM down to 0.001 mM in acidic pH between 3 and 6. The sorption followed a Langmuir model with a maximum capacity of 0.5 mmol/g. The removal is accomplished by an anion exchange mechanism. The rate constant for the sorption was found to be 9.6 x 10(-2) min-1. A column test shows that the fluoride ion was retained on the column until breakthrough point and the fluoride sorbed in the column can be eluted with 0.1 M NaOH. The column can be reused after being condition with hydrochloric acid at pH 4. The resin was tested and found to be effective for removal of fluoride from actual industrial wastewater.

  15. Perfluoroalkyl Cobalt(III) Fluoride and Bis(perfluoroalkyl) Complexes: Catalytic Fluorination and Selective Difluorocarbene Formation.

    Science.gov (United States)

    Leclerc, Matthew C; Bayne, Julia M; Lee, Graham M; Gorelsky, Serge I; Vasiliu, Monica; Korobkov, Ilia; Harrison, Daniel J; Dixon, David A; Baker, R Tom

    2015-12-30

    Four perfluoroalkyl cobalt(III) fluoride complexes have been synthesized and characterized by elemental analysis, multinuclear NMR spectroscopy, X-ray crystallography, and powder X-ray diffraction. The remarkable cobalt fluoride (19)F NMR chemical shifts (-716 to -759 ppm) were studied computationally, and the contributing paramagnetic and diamagnetic factors were extracted. Additionally, the complexes were shown to be active in the catalytic fluorination of p-toluoyl chloride. Furthermore, two examples of cobalt(III) bis(perfluoroalkyl)complexes were synthesized and their reactivity studied. Interestingly, abstraction of a fluoride ion from these complexes led to selective formation of cobalt difluorocarbene complexes derived from the trifluoromethyl ligand. These electrophilic difluorocarbenes were shown to undergo insertion into the remaining perfluoroalkyl fragment, demonstrating the elongation of a perfluoroalkyl chain arising from a difluorocarbene insertion on a cobalt metal center. The reactions of both the fluoride and bis(perfluoroalkyl) complexes provide insight into the potential catalytic applications of these model systems to form small fluorinated molecules as well as fluoropolymers.

  16. Electrochemical OFF-ON ratiometric chemodosimeters for the selective and rapid detection of fluoride.

    Science.gov (United States)

    Mani, Veerappan; Li, Wen-Yung; Gu, Jiun-An; Lin, Chun-Mao; Huang, Sheng-Tung

    2015-01-01

    We have described two "OFF-ON electrochemical latent ratiometric redox chemodosimeters", 1,4-Bis(tert-butyldimethylsiloxy)benzene (H2Q') and 1,4-Bis (tert-butyldimet hylsiloxy)-2-methoxybenzene (MH2Q') for the selective detection of inorganic fluoride. The electrochemical signals of hydroquinone (H2Q) and o-methoxy hydroquinone (MH2Q) within this latent redox probes (H2Q' and MH2Q') were completely masked by protecting their hydroxyl group as silylether (OFF state). The externally added fluoride ions triggered the deprotection of H2Q' and MH2Q' and unmasked the electrochemical properties of H2Q and MH2Q respectively. The electrochemical reporters (H2Q and MH2Q) presented a pair of redox peaks at the electrode surface (ON state) and the peak currents are linearly dependent with the concentration of fluoride which leading to the ratiometric detection of fluoride. The limit of detection (signal-to-noise ratio=3) observed for the probes are 23.8 µM and 2.38 µM for H2Q' and MH2Q' respectively. The deprotection is highly selective for fluoride over other anions investigated. The probes are highly stable and the proposed approach offers rapid response time and promising practical applicability. The proposed strategy holds great promise for the commencement of new H2Q based electrochemical probes by tuning the electrochemical behavior of H2Q. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Highly Selective Fluoride Recognition by a Simple Carbazole-based Hydrozone Derivative

    Institute of Scientific and Technical Information of China (English)

    TANG Li-jun; ZHAO Guo-you; HUANG Zhen-long; WANG Nan-nan; GUO Jiao-jiao

    2013-01-01

    A simple carbazole hydrozone derivative(1) was synthesized and used as an optical probe for fluoride recognition in CH3CN.Receptor 1 exhibited colorimetric and fluorescent dual-channel response to fluoride anions.Addition of fluoride to a receptor 1 solution in CH3CN induced a distinct color change from yellow to magenta,the solution also displayed significant fluorescence blue shift.Thus receptor 1 exhibited dual-channel responses to fluoride with a high selectivity and sensitivity.

  18. Fluoride removal by Al, Ti, and Fe hydroxides and coexisting ion effect.

    Science.gov (United States)

    Zhang, Jianfeng; Brutus, Timothy E; Cheng, Jiemin; Meng, Xiaoguang

    2017-07-01

    Batch experiments were conducted to evaluate fluoride removal by Al, Fe, and Ti-based coagulants and adsorbents, as well as the effects of coexisting ions and formation of aluminum-fluoride complexes on fluoride removal by co-precipitation with alum (Al2(SO4)3·18H2O). Aluminum sulfate was more efficient than the other coagulants for fluoride removal in the pH range between 6 and 8. Nano-crystalline TiO2 was more effective for fluoride removal than Al and Fe hydroxides in a pH range of 3-5. Coexisting anions in water decreased the removal of fluoride in the order: phosphate (2.5mg/L)>arsenate (0.1mg/L)>bicarbonate (200mg/L)>sulfate (100mg/L)=nitrate (100mg/L)>silicate (10mg/L) at a pH of 6.0. The effect of silicate became more significant at pH>7.0. Calcium and magnesium improved the removal of fluoride. Zeta-potential measurements determined that the adsorption of fluoride shifted the PZC of Al(OH)3 precipitates from 8.9 to 8.4, indicating the chemical adsorption of fluoride at the surface. The presence of fluoride in solution significantly increased the soluble aluminum concentration at pHfluoride during co-precipitation with aluminum sulfate. Copyright © 2017. Published by Elsevier B.V.

  19. Ion-selective electrode reviews

    CERN Document Server

    Thomas, J D R

    1982-01-01

    Ion-Selective Electrode Reviews, Volume 3, provides a review of articles on ion-selective electrodes (ISEs). The volume begins with an article on methods based on titration procedures for surfactant analysis, which have been developed for discrete batch operation and for continuous AutoAnalyser use. Separate chapters deal with detection limits of ion-selective electrodes; the possibility of using inorganic ion-exchange materials as ion-sensors; and the effect of solvent on potentials of cells with ion-selective electrodes. Also included is a chapter on advances in calibration procedures, the d

  20. Synthesis of Lithium Fluoride from Spent Lithium Ion Batteries

    Directory of Open Access Journals (Sweden)

    Daniela S. Suarez

    2017-05-01

    Full Text Available Lithium (Li is considered a strategic element whose use has significantly expanded. Its current high demand is due to its use in lithium ion batteries for portable electronic devices, whose manufacture and market are extensively growing every day. These days there is a great concern about the final disposal of these batteries. Therefore, the possibility of developing new methodologies to recycle their components is of great importance, both commercially and environmentally. This paper presents results regarding important operational variables for the dissolution of the lithium and cobalt mixed-oxide (LiCoO2 cathodes from spent lithium ion batteries (LIBs with hydrofluoric acid. The recovery and synthesis of Co and Li compounds were also investigated. The dissolution parameters studied were: temperature, reaction time, solid-liquid ratio, stirring speed, and concentration of HF. The investigated recovery parameters included: pH, temperature, and time with and without stirring. The final precipitation of lithium fluoride was also examined. The results indicate that an increase in the HF concentration, temperature, and reaction time favors the leaching reaction of the LiCoO2. Dissolutions were close to 60%, at 75 °C and 120 min with a HF concentration of 25% (v/v. The recovery of Co and Li were 98% and 80%, respectively, with purities higher than 94%. Co and Li compounds, such as Co3O4 and LiF, were synthesized. Furthermore, it was possible to almost completely eliminate the F− ions as CaF2.

  1. Chitosan-praseodymium complex for adsorption of fluoride ions from water

    Institute of Scientific and Technical Information of China (English)

    Eny Kusrini; Nofrijon Sofyan; Nyoman Suwartha; Gefin Yesya; Cindy Rianti Priadi

    2015-01-01

    Engineering of chitosan by praseodymium has been investigated to improve the adsorption properties as well as physical characteristics of chitosan. Modification of chitosan changes the original properties of chitosan so that it can be more suitable for ad-sorption of fluoride ions. In this study, chitosan-praseodymium (Chi-Pr) was synthesized by impregnation method. The Chi-Pr com-plex was characterized by scanning electron microscopic-energy dispersive X-ray spectroscopy (SEM-EDX), Fourier transform in-frared (FTIR) and employed as an adsorbent for removal of fluorides ions from water in the batch system. The variables such as con-tact time, concentration of Pr, adsorbent dose, initial concentration of fluoride ions, and competitor anions were studied. The adsorp-tion efficiency of fluoride ions (η) with increasing Pr loading into chitosan (5 wt.%, 10 wt.%, 15 wt.%, 20 wt.% and 25 wt.%) were 35.5%, 56.1%, 72.0%, 68.5% and 62.5%, respectively. The Chi-Pr (15 wt.%) complex had the highest fluoride removal efficiency (72.0%). The experimental data fitted well to the Langmuir isotherm with maximum adsorption capacity (qmax) of 15.87 mg/g and an equilibrium constant (kL) of 0.15 mg. Kinetic study revealed that the adsorption of fluoride ions from water followed pseudo-second-order model with a maximum adsorption capacity (q2) of 8.20 mg/g and a rate constant (k2) of 0.01 g/mg·min. Ad-sorption efficiency of fluoride ions in the simulated drinking water was diminished with the changes in pH levels. The presence of Pr3+in chitosan increased chitosan's performance as an adsorbent for adsorption of fluoride ions.

  2. Selective Adsorption of Sodium Aluminum Fluoride Salts from Molten Aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Leonard S. Aubrey; Christine A. Boyle; Eddie M. Williams; David H. DeYoung; Dawid D. Smith; Feng Chi

    2007-08-16

    Aluminum is produced in electrolytic reduction cells where alumina feedstock is dissolved in molten cryolite (sodium aluminum fluoride) along with aluminum and calcium fluorides. The dissolved alumina is then reduced by electrolysis and the molten aluminum separates to the bottom of the cell. The reduction cell is periodically tapped to remove the molten aluminum. During the tapping process, some of the molten electrolyte (commonly referred as “bath” in the aluminum industry) is carried over with the molten aluminum and into the transfer crucible. The carryover of molten bath into the holding furnace can create significant operational problems in aluminum cast houses. Bath carryover can result in several problems. The most troublesome problem is sodium and calcium pickup in magnesium-bearing alloys. Magnesium alloying additions can result in Mg-Na and Mg-Ca exchange reactions with the molten bath, which results in the undesirable pickup of elemental sodium and calcium. This final report presents the findings of a project to evaluate removal of molten bath using a new and novel micro-porous filter media. The theory of selective adsorption or removal is based on interfacial surface energy differences of molten aluminum and bath on the micro-porous filter structure. This report describes the theory of the selective adsorption-filtration process, the development of suitable micro-porous filter media, and the operational results obtained with a micro-porous bed filtration system. The micro-porous filter media was found to very effectively remove molten sodium aluminum fluoride bath by the selective adsorption-filtration mechanism.

  3. Removal of fluoride ions from water by adsorption onto carbonaceous materials produced from coffee grounds.

    Science.gov (United States)

    Ogata, Fumihiko; Tominaga, Hisato; Yabutani, Hitoshi; Kawasaki, Naohito

    2011-01-01

    Carbonaceous material for the removal of fluoride ions from water was prepared from coffee grounds (CGs) by calcination and subsequent HCl treatment. The characteristics of the CGs, including the surface area, mean pore diameter, pore volume, and surface functional groups were determined, and the morphological characteristics were evaluated using scanning electron microscopy. The adsorption isotherms, saturated amount of fluoride ions adsorbed, and the effect of contact time and temperature on the adsorption of fluoride ions were investigated for a sample of tap water. The specific surface area of CG calcined at 600° (CG600) was larger than that of CGs calcined at 400, 800, and 1000°. Phenolic, lactonic, and carboxyl groups were detected on the CG600 surface. The adsorption capacity of the carbonized CGs for fluoride was ranked in the order CG400 water.

  4. Ion-selective electrodes, 3

    Energy Technology Data Exchange (ETDEWEB)

    Pungor, E. (ed.)

    1981-01-01

    Thirty-two papers which were presented at the Third Symposium on Ion-Selective Electrodes are presented in this Proceedings. These papers dealt with standardization, fabrication, chemical properties of ion-selective electrodes and their application. Selected papers have been abstracted and indexed separately for the data base. (ATT)

  5. Removal of fluoride ions from aqueous solution at low pH using schwertmannite.

    Science.gov (United States)

    Eskandarpour, Akbar; Onyango, Maurice S; Ochieng, Aoyi; Asai, Shigeo

    2008-04-01

    Wastewater containing fluoride requires polishing after precipitation/coagulation treatment in order to meet stringent environmental legislation. Accordingly, adsorption characteristics of fluoride onto schwertmannite adsorbent were studied in a batch system with respect to changes in initial concentration of fluoride, equilibrium pH of sample solution, adsorbent dosage and co-existing ions. Equilibrium adsorption data were obtained at 295.6, 303 and 313 K, and are interpreted in terms of two-site Langmuir, Freundlich, Langmuir-Freundlich, Redlich-Peterson, Tóth and Dubinin-Radushkevitch isotherm models. The experimental and equilibrium modeling results revealed that the capacity of schwertmannite for fluoride is high but insensitive to changes in solution temperature. An increase in equilibrium pH of sample solution reduced significantly the fluoride removal efficiency. In binary component systems, inner-sphere complex forming species had negative effects on fluoride adsorption while outer-sphere complex forming species improved slightly the fluoride removal efficiency. The schwertmannite adsorbent was regenerable and had the ability to lower the fluoride concentration to acceptable levels.

  6. An in vitro assessment of fluoride uptake by tooth enamel from four different fluoride dentifrices.

    Science.gov (United States)

    Patil, V H; Anegundi, R T

    2014-10-01

    The aim of this study was to evaluate fluoride uptake by tooth enamel with four different fluoride dentifrices. Sixty human premolars extracted for orthodontic purpose were selected for the study. The teeth were covered with nail varnish leaving a window of 4 × 4 mm on the enamel surface of the buccal and lingual sides. The teeth were demineralised and were divided into four groups with 15 teeth in each group. The buccal window served as experimental and the lingual as control. The teeth were immersed in toothpaste slurry containing: sodium fluoride (Group A); sodium monofluorophosphate (Group B); stannous fluoride (Group C) and amine fluoride (Group D). The fluoride content in the etched superficial enamel layer in the windows was analysed using a fluoride ion-specific electrode. Within the parameters of this study, the uptake of fluoride was statistically significant in Group D (p fluoride by tooth enamel in an increasing order was Group A fluoride had the highest fluoride uptake.

  7. Inhibition of Chloride Induced Crevice Corrosion in Alloy 22 by Fluoride Ions

    Energy Technology Data Exchange (ETDEWEB)

    Carranza, R M; Rodr?guez, M A; Rebak, R B

    2005-10-09

    Alloy 22 (N06022) is highly resistant to localized corrosion. Alloy 22 may be susceptible to crevice corrosion in pure chloride (Cl{sup -}) solutions under aggressive environmental conditions. The effect of the fluoride (F{sup -}) over the crevice corrosion induced by chloride ions is still not well established. The objective of the present work was to explore the crevice corrosion resistance of this alloy to different mixtures of fluorides and chlorides. Cyclic potentiodynamic polarization (CPP) tests were conducted in deaerated aqueous solutions of pure halide ions and also in different mixtures of chloride and fluoride at 90 C and pH 6. The range of chloride concentration [Cl{sup -}] was 0.001 M {le} [Cl{sup -}] {le} 1 M and the range of molar fluoride to chloride ratio [F{sup -}]/[Cl{sup -}] was 0.1 {le} [F{sup -}]/[Cl{sup -}] {le} 10. Results showed that Alloy 22 was susceptible to crevice corrosion in all the pure chloride solutions but not in the pure fluoride solutions. Fluoride ions showed an inhibitor behavior only in mixtures with a molar ratio [F{sup -}]/[Cl{sup -}] > 2. For mixtures with a molar ratio [F{sup -}]/[Cl{sup -}] of 7 and 10 the inhibition of crevice corrosion was complete.

  8. Fluoride removal from water by zirconium (IV) doped chitosan bio ...

    African Journals Online (AJOL)

    Toshiba

    bio-composite was at par with commercial alumina to mitigate water fluoride limit .... analyzed for residual fluoride concentration by ion selective ..... zirconium (IV) doped chitosan were reused in another ... desalination in India: Review Article.

  9. A new colorimetric and fluorescent bis(coumarin)methylene probe for fluoride ion detection based on the proton transfer signaling mode

    Energy Technology Data Exchange (ETDEWEB)

    Mahapatra, Ajit Kumar, E-mail: akmahapatra@rediffmail.com; Maiti, Kalipada; Sahoo, Prithidipa; Nandi, Prasanta Kumar

    2013-11-15

    A new turn-on fluorescent and colorimetric sensor, oxidized bis(coumarin)methane (1) for fluoride in acetonitrile was designed and synthesized. The binding ability evaluated by UV–vis and fluorescence titration experiments reveals that 1 can selectively interact with fluoride. Upon addition of fluoride to receptor 1 in acetonitrile solution, the appearance of a new absorption band around 349 nm showed a color change from colorless to yellow, which can provide a way of ‘naked eye’ detection of fluorides. The spectral change of 1 is due to the anion induced deprotonation and hence an increase in charge density and rigidity of the receptor molecule. Furthermore, the binding mode with fluoride was investigated by {sup 1}H NMR titration experiments. Again, the deprotonation of oxidized bis(coumarin)methane 1 is responsible for the color change. -- Graphical abstract: A new colorimetric and fluorescent bis(coumarin)methylene probe for fluoride ion detection based on the proton transfer signaling mode. Highlights: • The first report of conjugated biscoumarin-based colorimetric chemosensor. • Oxidized bis(coumarin)methane acts as colorimetric reporter. • The oxidized coumarin moiety might modulate the internal charge transfer (ICT). • Fluorescence turn-on sensing of fluoride.

  10. Electrodialytic removal of fluoride and calcium ions to recover phosphate from fertilizer industry wastewater

    Directory of Open Access Journals (Sweden)

    Arseto Yekti Bagastyo

    2017-09-01

    Full Text Available The fertilizer industry generates wastewater rich in phosphate and fluoride content, with concentration as high as 4540 and 9720 mg L−1, respectively. The untreated wastewater may enhance the growth of algae, promote eutrophication, and create serious effects on environmental health and aquatic life. Therefore, this wastewater has to be treated before releasing into the environment. This study evaluates the performance of a three-compartment electrodialysis reactor to remove fluoride and calcium ions, and recover phosphate present in the wastewater, for possible further use in the fertilizer industry. The experiments were conducted in a batch system at room temperature. A 4 L of wastewater was electrodialysed using three different electrical current (i.e., 0.5, 0.75, and 1.0 A and two different membrane surface areas (i.e., 100 and 200 cm2. The highest removal of fluoride ions was up to 260 mg L−1 (2.7% by applying 1 A of current and 100 cm2 membrane area. No substantial increase of fluoride and calcium removal was observed for 200 cm2 membrane area. Interestingly, the amount of the remaining phosphate was high (i.e., only 1% removal, implying a very efficient recovery in the feed. The energy required for fluoride ion transfer was much lower than for phosphate ion, i.e., up to 6 vs. 0.12 mol kWh−1, suggesting that a higher removal of fluoride can possibly be achieved by limiting migration of phosphate ion through the membrane.

  11. A study of fluoride groundwater occurrence in Nathenje, Lilongwe, Malawi

    Science.gov (United States)

    Msonda, K. W. M.; Masamba, W. R. L.; Fabiano, E.

    A study was carried out to determine fluoride concentration in groundwaters of Nathenje area situated in Lilongwe District in the central region of Malawi. Water samples were collected from 176 boreholes and shallow wells during different months in 2001 and 2002. Samples were then analysed for fluoride by using a fluoride electrode and an ion selective meter. The results showed that fluoride concentrations for the rainy season varied from dental fluorosis in areas where the fluoride concentration was high.

  12. A novel smart supramolecular organic gelator exhibiting dual-channel responsive sensing behaviours towards fluoride ion via gel-gel states.

    Science.gov (United States)

    Mehdi, Hassan; Pang, Hongchang; Gong, Weitao; Dhinakaran, Manivannan Kalavathi; Wajahat, Ali; Kuang, Xiaojun; Ning, Guiling

    2016-07-07

    A novel smart supramolecular organic gelator G-16 containing anion and metal-coordination ability has been designed and synthesized. It shows excellent and robust gelation capability as a strong blue fluorescent supramolecular organic gel OG in DMF. Addition of Zn(2+) produced Zn(2+)-coordinated supramolecular metallogel OG-Zn. Organic gel OG and organometallic gel OG-Zn exhibited efficient and different sensing behaviors towards fluoride ion due to the variation in self-assembling nature. Supramolecular metallogel OG-Zn displayed specific selectivity for fluoride ion and formed OG-Zn-F with dramatic color change from blue to blue green in solution and gel to gel states. Furthermore after directly addition of fluoride into OG produced fluoride containing organic gel OG-F with drastically modulation in color from blue to greenish yellow fluorescence via strong aggregation-induced emission (AIE) property. A number of experiments were conducted such as FTIR, (1)H NMR, and UV/Vis spectroscopies, XRD, SEM and rheology. These results revealed that the driving forces involved in self-assembly of OG, OG-Zn, OG-Zn-F and OG-F were hydrogen bonding, metal coordination, π-π interactions, and van der Waal forces. In contrast to the most anion responsive gels, particularly fluoride ion responsive gels showed gel-sol state transition on stimulation by anions, the gel state of OG and OG-Zn did not show any gel-to-sol transition during the whole F(-) response process.

  13. Visual sensing of fluoride ions by dipyrrolyl derivatives bearing electron-withdrawing groups

    Indian Academy of Sciences (India)

    Tamal Ghosh; Bhaskar G Maiya

    2004-01-01

    Two new, easy-to-prepare dipyrrolyl derivatives endowed with electron-withdrawing quinone or dicyano functionalities in their architecture permit the detection of fluoride ions under visual (naked-eye) as well as optical (absorption and fluorescence) and electrochemical conditions in organic solvents.

  14. Nuclear quantum effects in water exchange around lithium and fluoride ions

    CERN Document Server

    Wilkins, David M; Dang, Liem X

    2015-01-01

    We employ classical and ring polymer molecular dynamics simulations to study the effect of nuclear quantum fluctuations on the structure and the water exchange dynamics of aqueous solutions of lithium and fluoride ions. While we obtain reasonably good agreement with experimental data for solutions of lithium by augmenting the Coulombic interactions between the ion and the water molecules with a standard Lennard-Jones ion-oxygen potential, the same is not true for solutions of fluoride, for which we find that a potential with a softer repulsive wall gives much better agreement. A small degree of destabilization of the first hydration shell is found in quantum simulations of both ions when compared with classical simulations, with the shell becoming less sharply defined and the mean residence time of the water molecules in the shell decreasing. In line with these modest differences, we find that the mechanisms of the exchange processes are unaffected by quantization, so a classical description of these reaction...

  15. Boron-dipyrromethene based reversible and reusable selective chemosensor for fluoride detection.

    Science.gov (United States)

    Madhu, Sheri; Ravikanth, Mangalampalli

    2014-02-03

    We synthesized benzimidazole substituted boron-dipyrromethene 1 (BODIPY 1) by treating 3,5-diformyl BODIPY 2 with o-phenylenediamine under mild acid catalyzed conditions and characterized by using various spectroscopic techniques. The X-ray structure analysis revealed that the benzimidazole NH group is involved in intramolecular hydrogen bonding with fluoride atoms which resulted in a coplanar geometry between BODIPY and benzimidazole moiety. The presence of benzimidazole moiety at 3-position of BODIPY siginificantly altered the electronic properties, which is clearly evident in bathochromic shifts of absorption and fluorescence bands, improved quantum yields, increased lifetimes compared to BODIPY 2. The anion binding studies indicated that BODIPY 1 showed remarkable selectivity and specificity toward F(-) ion over other anions. Addition of F(-) ion to BODIPY 1 resulted in quenching of fluorescence accompanied by a visual detectable color change from fluorescent pink to nonfluorescent blue. The recognition mechanism is attributed to a fluoride-triggered disruption of the hydrogen bonding between BODIPY and benzimidazole moieties leading to (i) noncoplanar geometry between BODIPY and benzimidazole units and (ii) operation of photoinduced electron transfer (PET) from benzimidazole moiety to BODIPY unit causing quenching of fluorescence. Interestingly, when we titrated the nonfluorescent blue 1-F(-) solution with TFA resulted in a significant enhancement of fluorescence intensity (15-fold) because the PET quenching is prevented due to protonation of benzimidazole group. Furthermore, the reversibility and reusability of sensor 1 for the detection of F(-) ion was tested for six cycles indicating the sensor 1 is stable and can be used in reversible manner.

  16. Relationships of human plasma fluoride and bone fluoride to age

    Energy Technology Data Exchange (ETDEWEB)

    Parkins, F.M.; Tinanoff, N.; Moutinho, M.; Anstey, M.B.; Waziri, M.H.

    1976-04-01

    There is evidence that fluoride levels in plasma correlate with the fluoride content in bones. The authors determined whether or not fluoride in plasma and bones might correlate with age. In 41 in-patients at the University Hospital, Iowa City, 36 of whom had been residing in fluoridated communities plasma fluoride was determined in the fasting stage by the fluoride ion selective electrode. The teeth of these children were compared with those of a neighboring city where the natural fluoride content in drinking water was 0.1 ppm. For the second sampling 42 months following the beginning of the program only 10 and 11 year old children - who had been 6 and 7 years old at the beginning of the experiment - were selected. Twenty-five boys and girls in each group were compared with a similar group of children as controls. After 28 months (approximately 33 rinsing with sodium fluoride solution) the DMF index in the fluoride-treated children was 18.4% less than in the controls. In the second group among 10 and 11 year old children after 42 months with 55 rinsings the difference was 35.0%. The author acknowledged that factors other than applications of sodium fluoride may have contributed to the prevention of caries in the fluoride-treated groups.

  17. Effect of grinding and fluoride-gel exposure on strength of ion-exchanged porcelain.

    Science.gov (United States)

    Anusavice, K J; Hojjatie, B; Chang, T C

    1994-08-01

    Strengthening of dental porcelain through a diffusion heat treatment at 450 degrees C of a potassium-enriched, ion-exchange surface coating has been demonstrated in several recent studies. However, little attention has been focused on the potential strength reduction of these materials when the treated surfaces are ground or etched under clinically simulated conditions. The objective of this study was to test the hypothesis that partial removal of the surface layers of ion-exchanged porcelains by grinding or exposure to acidulated fluoride gel will significantly reduce their flexure strength. Nine groups of body porcelain disks were ion-exchanged at 450 degrees C for 30 min. One of these groups was subjected to ion exchange and no further surface treatment. Eight specimen groups were subjected to the following procedures after ion exchange: grinding to depths of 50 microns, 100 microns, 150 microns, 200 microns, and 250 microns, and exposure to acidulated fluoride for 30 min, 60 min, and 300 min. A tenth group (FC) was fired at 960 degrees C and fast-cooled in air, but the disks were not subjected to the ion-exchange treatment. Surface stress was calculated from measured values of cracks induced in the treated surfaces. Fluoride exposure for up to 60 min resulted in a significant decrease in surface compression (P 0.05).

  18. Ion spatial distributions at the liquid-vapor interface of aqueous potassium fluoride solutions.

    Science.gov (United States)

    Brown, Matthew A; D'Auria, Raffaella; Kuo, I-F William; Krisch, Maria J; Starr, David E; Bluhm, Hendrik; Tobias, Douglas J; Hemminger, John C

    2008-08-28

    X-Ray photoemission spectroscopy operating under ambient pressure conditions is used to probe ion distributions throughout the interfacial region of a free-flowing aqueous liquid micro-jet of 6 M potassium fluoride. Varying the energy of the ejected photoelectrons by carrying out experiments as a function of X-ray wavelength measures the composition of the aqueous-vapor interfacial region at various depths. The F(-) to K(+) atomic ratio is equal to unity throughout the interfacial region to a depth of 2 nm. The experimental ion profiles are compared with the results of a classical molecular dynamics simulation of a 6 M aqueous KF solution employing polarizable potentials. The experimental results are in qualitative agreement with the simulations when integrated over an exponentially decaying probe depth characteristic of an APPES experiment. First principles molecular dynamics simulations have been used to calculate the potential of mean force for moving a fluoride anion across the air-water interface. The results show that the fluoride anion is repelled from the interface, consistent with the depletion of F(-) at the interface revealed by the APPES experiment and polarizable force field-based molecular dynamics simulation. Together, the APPES and MD simulation data provide a detailed description of the aqueous-vapor interface of alkali fluoride systems. This work offers the first direct observation of the ion distribution at an aqueous potassium fluoride solution interface. The current experimental results are compared to those previously obtained for saturated solutions of KBr and KI to underscore the strong difference in surface propensity between soft/large and hard/small halide ions in aqueous solution.

  19. Oxidative aliphatic C-H fluorination with manganese catalysts and fluoride ion.

    Science.gov (United States)

    Liu, Wei; Huang, Xiongyi; Groves, John T

    2013-12-01

    Fluorination is a reaction that is useful in improving the chemical stability and changing the binding affinity of biologically active compounds. The protocol described here can be used to replace aliphatic, C(sp(3))-H hydrogen in small molecules with fluorine. Notably, isolated methylene groups and unactivated benzylic sites are accessible. The method uses readily available manganese porphyrin and manganese salen catalysts and various fluoride ion reagents, including silver fluoride (AgF), tetrabutylammonium fluoride and triethylamine trihydrofluoride (TREAT·HF), as the source of fluorine. Typically, the reactions afford 50-70% yield of mono-fluorinated products in one step. Two representative examples, the fragrance component celestolide and the nonsteroidal anti-inflammatory drug ibuprofen, are described; they produced useful isolated quantities (250-300 mg, ~50% yield) of fluorinated material over periods of 1-8 h. The procedures are performed in a typical fume hood using ordinary laboratory glassware. No special precautions to rigorously exclude water are required.

  20. Ion-chromatographic determination of chloride and fluoride in electrolyte from the halogen tin-plating process.

    Science.gov (United States)

    Korth, W; Ellis, J

    1984-06-01

    A simple and rapid procedure is proposed for the determination of chloride and free fluoride in tin electroplating fluid. Suppressor-column ion-chromatography is used after oxidation of hexafluorostannate(II) to hexafluorostannate(IV) with hydrogen peroxide. Concurrent determination of tin(II) and total tin then allows calculation of the concentrations of fluoride, hexafluorostannate(II) and hexafluorostannate(IV).

  1. Ion selectivity of graphene nanopores

    OpenAIRE

    Rollings, Ryan C.; Kuan, Aaron T.; Golovchenko, Jene A.

    2016-01-01

    As population growth continues to outpace development of water infrastructure in many countries, desalination (the removal of salts from seawater) at high energy efficiency will likely become a vital source of fresh water. Due to its atomic thinness combined with its mechanical strength, porous graphene may be particularly well-suited for electrodialysis desalination, in which ions are removed under an electric field via ion-selective pores. Here, we show that single graphene nanopores prefer...

  2. Ion selectivity of graphene nanopores

    Science.gov (United States)

    Rollings, Ryan C.; Kuan, Aaron T.; Golovchenko, Jene A.

    2016-04-01

    As population growth continues to outpace development of water infrastructure in many countries, desalination (the removal of salts from seawater) at high energy efficiency will likely become a vital source of fresh water. Due to its atomic thinness combined with its mechanical strength, porous graphene may be particularly well-suited for electrodialysis desalination, in which ions are removed under an electric field via ion-selective pores. Here, we show that single graphene nanopores preferentially permit the passage of K+ cations over Cl- anions with selectivity ratios of over 100 and conduct monovalent cations up to 5 times more rapidly than divalent cations. Surprisingly, the observed K+/Cl- selectivity persists in pores even as large as about 20 nm in diameter, suggesting that high throughput, highly selective graphene electrodialysis membranes can be fabricated without the need for subnanometer control over pore size.

  3. Selective Access to Heterocyclic Sulfonamides and Sulfonyl Fluorides via a Parallel Medicinal Chemistry Enabled Method.

    Science.gov (United States)

    Tucker, Joseph W; Chenard, Lois; Young, Joseph M

    2015-11-09

    A sulfur-functionalized aminoacrolein derivative is used for the efficient and selective synthesis of heterocyclic sulfonyl chlorides, sulfonyl fluorides, and sulfonamides. The development of a 3-step parallel medicinal chemistry (PMC) protocol for the synthesis of pyrazole-4-sulfonamides effectively demonstrates the utility of this reagent. This reactivity was expanded to provide rapid access to other heterocyclic sulfonyl fluorides, including pyrimidines and pyridines, whose corresponding sulfonyl chlorides lack suitable chemical stability.

  4. Selective Colorimetric Fluoride Sensor: A Heteroditopic Re-ceptor Combining Pyrrolic Amide with Urea

    Institute of Scientific and Technical Information of China (English)

    YIN Zhenming; LIU Shangyuan

    2009-01-01

    A heteroditopic anion receptor, beating one pyrrolic amide site and a urea site, has been synthesized. UV-Vis spectrum studies in CH3CN solution revealed that the receptor had higher anion binding ability than the homoditopic one. A naked-eye detectable color change, from colorless to yellow, of the receptor solution took place when fluoride was added, which indicates that the receptor has potential application to selective colorimetric fluo-ride sensing.

  5. Transition-state structure for the hydronium-ion-promoted hydrolysis of α-d-glucopyranosyl fluoride

    National Research Council Canada - National Science Library

    Tang, Ariel; Chan, Jefferson; Bennet, Andrew J

    2015-01-01

    The transition state for the hydronium-ion-promoted hydrolysis of α- d -glucopyranosyl fluoride in water has been characterized by combining multiple kinetic isotope effect measurements with theoretical modelling...

  6. Transition-state structure for the hydronium-ion-promoted hydrolysis of [alpha]-D-glucopyranosyl fluoride

    National Research Council Canada - National Science Library

    Chan, Jefferson; Tang, Ariel; Bennet, Andrew J

    2015-01-01

    The transition state for the hydronium-ion-promoted hydrolysis of [alpha]-D-glucopyranosyl fluoride in water has been characterized by combining multiple kinetic isotope effect measurements with theoretical modelling...

  7. PREPARATION AND CHARACTERIZATION OF ION EXCHANGE MEMBRANES BASED ON POLYVINYLIDENE FLUORIDE

    Institute of Scientific and Technical Information of China (English)

    Bo Tian; Chuan-wei Yan; Fu-hui Wang

    2004-01-01

    A new ion exchange membrane based on polyvinylidene fluoride (PVDF) and sulfonated poly(styrenedivinylbenzene) was prepared by in-situ polymerization. The incorporation of sulfonic groups into the polyvinylidene fluoride composite membrane was confirmed by infrared spectroscopy (IR), ion exchange capacity (IEC) and energy dispersive X-ray analysis (EDAX). Area resistance, IEC and water uptake of the treated membrane were evaluated. When area resistance in NaCl aqueous solution at 25℃, IEC is as high as 2.43 millimoles per gram of the wet membrane. The hydrophilicity of PVDF membrane is also significantly improved after treatment. When 60% of crosslinked membrane was sulfonated at 80℃ for 6 h, water uptake of the treated membrane can attain 64.7%.

  8. Effect of a static magnetic fields and fluoride ions on the antioxidant defense system of mice fibroblasts.

    Science.gov (United States)

    Kurzeja, Ewa; Synowiec-Wojtarowicz, Agnieszka; Stec, Małgorzata; Glinka, Marek; Gawron, Stanisław; Pawłowska-Góral, Katarzyna

    2013-07-18

    The results of studies on the biological influence of magnetic fields are controversial and do not provide clear answers regarding their impact on cell functioning. Fluoride compounds are substances that influence free radical processes, which occur when the reactive forms of oxygen are present. It is not known whether static magnetic fields (SMF) cause any changes in fluoride assimilation or activity. Therefore, the aim of this work was to determine the potential relationship between magnetic field exposure to, and the antioxidant system of, fibroblasts cultured with fluoride ions. Three chambers with static magnetic fields of different intensities (0.4, 0.6, and 0.7 T) were used in this work. Fluoride ions were added at a concentration of 0.12 mM, which did not cause the precipitation of calcium or magnesium. The results of this study show that static magnetic fields reduce the oxidative stress caused by fluoride ions and normalize the activities of antioxidant enzymes, including superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). Static magnetic fields modify the energy state of fibroblasts, causing an increase in the ATP concentration and a decrease in the MDA concentration. These results suggest that exposure to fluoride and an SMF improves the tolerance of cells to the oxidative stress induced by fluoride ions.

  9. Structural stability, acidity, and halide selectivity of the fluoride riboswitch recognition site

    KAUST Repository

    Chawla, Mohit

    2015-01-14

    Using static and dynamics DFT methods we show that the Mg2+/F-/phosphate/water cluster at the center of the fluoride riboswitch is stable by its own and, once assembled, does not rely on any additional factor from the overall RNA fold. Further, we predict that the pKa of the water molecule bridging two Mg cations is around 8.4. We also demonstrate that the halide selectivity of the fluoride riboswitch is determined by the stronger Mg-F bond, which is capable of keeping together the cluster. Replacing F- with Cl- results in a cluster that is unstable under dynamic conditions. Similar conclusions on the structure and energetics of the cluster in the binding pocket of fluoride-inhibited pyrophosphatase suggest that the peculiarity of fluoride is in its ability to establish much stronger metal-halide bonds.

  10. To immobilize polyethylene glycol-borate ester/lithium fluoride in graphene oxide/poly(vinyl alcohol) for synthesizing new polymer electrolyte membrane of lithium-ion batteries

    OpenAIRE

    Huang, Y.F.; Zhang, M. Q.; M. Z. Rong; W. H. Ruan

    2017-01-01

    Polymer electrolyte membranes (PEMs) are potentially applicable in lithium-ion batteries with high safety, low cost and good performance. Here, to take advantages of ionic conductivity and selectivity of borate ester-functionalized small molecules as well as structural properties of polymer nanocomposite, a strategy of immobilizing as-synthesized polyethylene glycol-borate ester/lithium fluoride (B-PEG/LiF) in graphene oxide/poly(vinyl alcohol) (GO/PVA) to prepare a PEM is put forward. Chemic...

  11. Gas-phase energetics of thorium fluorides and their ions.

    Science.gov (United States)

    Irikura, Karl K

    2013-02-14

    Gas-phase thermochemistry for neutral ThF(n) and cations ThF(n)(+) (n = 1-4) is obtained from large-basis CCSD(T) calculations, with a small-core pseudopotential on thorium. Electronic partition functions are computed with the help of relativistic MRCI calculations. Geometries, vibrational spectra, electronic fine structure, and ion appearance energies are tabulated. These results support the experimental results by Lau, Brittain, and Hildenbrand for the neutral species, except for ThF. The ion thermochemistry is presented here for the first time.

  12. Corrosion behaviour of TiN and ZrN in the environment containing fluoride ions.

    Science.gov (United States)

    Joska, Ludek; Fojt, Jaroslav; Hradilova, Monika; Hnilica, Frantisek; Cvrcek, Ladislav

    2010-10-01

    Nowadays, a wide range of materials for human implants is used. To reach the required properties of implants, coatings are applied in some cases. This contribution is focused on the corrosion properties of TiN and ZrN layers on cp-titanium (commercially pure titanium) under environment modelling conditions in an oral cavity. Measurements were done in artificial saliva and a physiological solution unbuffered and buffered to a pH value of 4.2 with the addition of fluoride ions up to 4000 ppm. Standard corrosion electrochemical techniques were applied. Both types of layers were stable in both model saliva and physiological solution with non-adjusted pH. The decrease in pH to 4.2 resulted in a minor decrease of corrosion resistance in all cases, but polarization resistance was still in the order of 10(5) Ω cm². An important change in a specimens' behaviour was noticed in the presence of fluoride ions. TiN was stable in the highest concentration of fluorides used. The ZrN layers were destabilized in an environment containing a few hundred ppm of fluoride ions. As for TiN, the decisive factor is the influence of porosity; the corrosion resistance of ZrN is limited. From the corrosion point of view, the application of the TiN-based barrier layers in dental implantology is more advisable than the use of ZrN, provided that the application of a barrier is inevitable.

  13. Screening biological traits and fluoride contents of native vegetations in arid environments to select efficiently fluoride-tolerant native plant species for in-situ phytoremediation.

    Science.gov (United States)

    Boukhris, Asma; Laffont-Schwob, Isabelle; Mezghani, Imed; El Kadri, Lefi; Prudent, Pascale; Pricop, Anca; Tatoni, Thierry; Chaieb, Mohamed

    2015-01-01

    High fluoride pollution has been detected in the surrounding soils of the coastal superphosphate industries in the Gulf of Gabes (Southeast of Tunisia). A study was conducted in vicinity of factories analysing plant functional traits combined with plant fluoride accumulation and soil metal concentrations aiming to screen more efficiently native plant species tolerant to this pollution. Aerial parts of 18 plant species out of the 10 most abundant species per site were harvested on two polluted sites of Gabes and Skhira at the vicinity of the factories and on the less polluted site of Smara. Native plant species accumulated fluoride following the gradient of soil pollution. Fluoride contents of plant aerial parts ranged from 37 mg kg(-1) to 360 mg kg(-1) and five plant species were only found in the most polluted site. However these latter had low biomass and soil cover. Crossing biological traits and fluoride contents, a selection grid for potentially restorative plant species enabled the selection of three native perennials i.e. Rhanterium suaveolens, Atractylis serratuloides and, Erodium glaucophyllum as potential candidates for an in-situ phytoremediation program on arid fluoride-polluted sites. This approach may be used in other fluoride-polluted Mediterranean environments.

  14. Colorimetric and fluorimetric response of salicylaldehyde dithiosemicarbazone towards fluoride, cyanide and copper ions: Spectroscopic and TD-DFT studies

    Science.gov (United States)

    Harikrishnan, Vengayil K.; Basheer, Sabeel M.; Joseph, Nithin; Sreekanth, Anandaram

    2017-07-01

    The sensing mechanism of salicylaldehyde phenyldithiosemicarbazone (SDTSC) chemosensor has been investigated by spectroscopic and TD-DFT methods. The SDTSC shows colourimetric and spectral changes towards fluoride, cyanide and copper ions. The interaction between SDTSC with fluoride, cyanide and copper ions was examined through their absorption and fluorescence behaviour, and found that SDTSC has more sensing ability towards Cu2 + ion than CN- and F- ions. The 1H NMR titration with SDTSC and F- gives the structural changes in the sensing process. The reversibility of SDTSC was also evaluated and thus it is confirmed as a reusable chemosensor which can be clarified by the ;Read-Erase-Read-Write; logic system. The DFT and TD-DFT calculations give the detailed sensing mechanism of SDTSC towards fluoride ion. The potential energy surface (PES) analysis confirms the excited state electron transfer mechanism.

  15. A new class of efficient 4-[(nitro substituted-phenyl)-hydrazonomethyl]- 1-phenyl-1H-pyrazole-3-carboxylate derived colorimetric chemosensor for selective sensing of fluoride and other biologically important anions

    Indian Academy of Sciences (India)

    SUMAN SWAMI; ARUNAVA AGARWALA; BABITA MALIK; RAHUL SHRIVASTAVA

    2016-09-01

    A new class of efficient colorimetric chemosensors derived from 4-[(nitro substituted-phenyl)-hydrazonomethyl]-1-phenyl-1H-pyrazole-3-carboxylate have been synthesized and characterized. The synthesized receptors exhibit instant color change from yellow to dark purple along with significant bathochromicshifts when interacted with fluoride ions. The UV-Visible and ¹H NMR titration experiments revealed that 4-[(4-nitro-phenyl)-hydrazonomethyl]-1-phenyl-1H-pyrazole-3-carboxylate derivatives showed selective sensing of fluoride ions in preference to Cl⁻, Br⁻, I⁻, PF⁻⁻, HSO₄⁻, ClO₄⁻ , CH₃COO⁻ and H₂PO₄⁻ ions while 4-[2,4-dinitro-phenyl)-hydrazonomethyl]-1-phenyl-1H-pyrazole-3-carboxylate derivatives showed sensing of acetate, dihydrogen phosphate ion and fluoride ion in organic media.

  16. Dentifrice Fluoride

    Science.gov (United States)

    Rakita, Philip E.

    2004-05-01

    The effectiveness of the fluoride ion in lowering the incidence of dental caries is a major factor in the field of dental health. Observations and research studies in the first half of the 20th century have lead to the widespread adoption of fluoridated water and the use of inorganic fluoride compounds in oral care products, such as toothpaste and dental rinses. This article provides a brief review of the types of compounds used and the chemistry involved.

  17. Tuning the Colors of the Dark Isomers of Photochromic Boron Compounds with Fluoride Ions: Four-State Color Switching.

    Science.gov (United States)

    Mellerup, Soren K; Rao, Ying-Li; Amarne, Hazem; Wang, Suning

    2016-09-02

    Combining a three-coordinated boron (BMes2) moiety with a four-coordinated photochromic organoboron unit leads to a series of new diboron compounds that undergo four-state reversible color switching in response to stimuli of light, heat, and fluoride ions. Thus, these hybrid diboron systems allow both convenient color tuning/switching of such photochromic systems, as well as visual fluoride sensing by color or fluorescent emission color change.

  18. Ultra-Trace Detection of Fluoride Ion and Hydrofluoric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Timothy M. Swager

    2005-03-17

    Describes general synthetic strategies developed under this grant to control interchain electronic communications within conjugated polymers (CPs). Novel chemical architectures built on iptycenes, metallorotaxanes, and canopied pyrroles restrict the dimensionality of electronic structures responsible for excition and charge transport. Structure-property relationships emerging from studies of selected systems are discussed, focusing on their implications for the sensitivity of these materials as sensors.

  19. Assessment of total and soluble fluoride content in commercial dentifrices in Davangere: A cross sectional survey

    Directory of Open Access Journals (Sweden)

    D J Veeresh

    2014-01-01

    Full Text Available Introduction: The major reason for decline in dental caries across globe is because of widespread use of fluoride dentifrices. For a fluoride dentifrice to be effective in the control of dental caries, an adequate concentration of the fluoride must be soluble. Objective: To assess soluble fluoride and total fluoride content in selected commercial dentifrices in Davangere. Materials and Methods: The soluble fluoride and total fluoride content in six selected commercial dentifrices in Davangere were assessed and expressed as ppm of fluoride (F (mgF/g. Total fluoride and soluble fluoride was determined using an ion-specific electrode. Descriptive statistics applied to assess the mean total fluoride and soluble fluoride. Results: The total fluoride and soluble fluoride concentrations were approximately near to 1,000 ppm. Among the six dentifrices evaluated, four contained sodium fluoride (NaF and two contained sodium monofluorophosphate (Na MFP as fluoride compound. Conclusions: All the fluoridated dentifrices evaluated in this study contain adequate amount of soluble and total fluoride.

  20. Mechanical synthesis and structural properties of the fast fluoride-ion conductor PbSnF4

    Science.gov (United States)

    Fujisaki, Fumika; Mori, Kazuhiro; Yonemura, Masao; Ishikawa, Yoshihisa; Kamiyama, Takashi; Otomo, Toshiya; Matsubara, Eiichiro; Fukunaga, Toshiharu

    2017-09-01

    A fluoride-ion conductor, γ-PbSnF4, was synthesized by the mechanical milling. In addition, β-PbSnF4 was obtained by aging the γ-PbSnF4 at 473 K. The electrical conductivity of β-PbSnF4 is relatively higher than that of γ-PbSnF4 at 298 K. The crystal structure analysis of γ- and β-PbSnF4 was carried out using neutron diffraction data. From the obtained occupancies, fluoride ions were located at the Fγ(1) normal site (62%) and Fγ(2) interstitial site (38%) in γ-PbSnF4 and the Fβ(1) normal site (31%), Fβ(2) normal site (25%), and Fβ(3) interstitial site (44%) in β-PbSnF4. In particular, the number of fluoride ions at the F interstitial site increased after the γ-to-β phase transition: 38% at Fγ(2) to 44% at Fβ(3). It is most likely that the ratio of fluoride ions to vacancies (or the effective carrier concentration) was optimized in the ;-Fβ(1)-Fβ(3)-Fβ(3)-Fβ(1)-; conduction pathways of fluoride ions in β-PbSnF4.

  1. Heavy-ion induced modification of lithium fluoride observed by scanning force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, A.; Neumann, R.; Schwartz, K.; Steckenreiter, T.; Trautmann, C.

    1997-12-01

    To study ion-induced damages in single crystals of lithium fluoride with scanning force microscopy (SFM), samples were irradiated with several heavy-ion species of a kinetic energy of 11.4 MeV per nucleon at the linear accelerator UNILAC of GSI. As concluded from a previous analysis of ion tracks in LiF by optical absorption spectroscopy and small-angle X-ray scattering, single point defects occur in a track halo with a radius of about 15-30 nm, whereas defect aggregates are formed in a track core region possessing a radius of only about 1-2 nm. These aggregates can be attacked by chemical etching if the energy loss along the ion trajectory surpasses a critical value of about 1 keV/Aa. SFM images of etched as well as unetched sample surfaces revealed new damage characteristics: Etched ion track profiles directed parallel to the ion trajectories exhibit a sequence of single etch pits with an average distance of about 140 nm. After exposure to heavy-ion irradiation at normal incidence, the unetched LiF surface is covered with round hillocks with a mean diameter of 55(8) nm and heights in the order of 3 nm. (orig.)

  2. Imaging of Fluoride Ion in Living Cells and Tissues with a Two-Photon Ratiometric Fluorescence Probe

    Directory of Open Access Journals (Sweden)

    Xinyue Zhu

    2015-01-01

    Full Text Available A reaction-based two-photon (TP ratiometric fluorescence probe Z2 has been developed and successfully applied to detect and image fluoride ion in living cells and tissues. The Z2 probe was designed designed to utilize an ICT mechanism between n-butylnaphthalimide as a fluorophore and tert-butyldiphenylsilane (TBDPS as a response group. Upon addition of fluoride ion, the Si-O bond in the Z2 would be cleaved, and then a stronger electron-donating group was released. The fluorescent changes at 450 and 540 nm, respectively, made it possible to achieve ratiometric fluorescence detection. The results indicated that the Z2 could ratiometrically detect and image fluoride ion in living cells and tissues in a depth of 250 μm by two-photon microscopy (TPM.

  3. A naphthalene benzimidazole-based chemosensor for the colorimetric and on-off fluorescent detection of fluoride ion

    Science.gov (United States)

    Li, Dongmei; Zhong, Zhimin; Zheng, Gengxiu; Tian, Zhongzhen

    2017-10-01

    A novel naphthalene benzimidazole (NBI)-based chemosensor (D2) was developed for fluoride ion (F-) detection. The absorption spectrum of D2 changed dramatically from yellow to blue in the visible region accompanied with a 225 nm red shift of its absorption maximum upon the addition of F- in DMSO. D2 also exhibited a fluorescence turn-off response towards the fluoride ion. The emission intensity of D2 decreased drastically along the increasing F- concentration and the detection limit for F- was as low as 3.2 × 10- 9 mol/L. 1H NMR and HRMS-ESI results indicated that the formation of NBI-O- through the desilylation reaction of F- with NBI-OSi was responsible for the spectral changes. Overall, this kind of NBI-type molecules represent a new type chemosensor for the spectral detection of fluoride ion in solution.

  4. Effect of resin composites with sodium trimetaphosphate with or without fluoride on hardness, ion release and enamel demineralization.

    Science.gov (United States)

    Tiveron, Adelisa Rodolfo Ferreira; Delbem, Alberto Carlos Botazzo; Gaban, Gabriel; Sassaki, Kikue Takebayashi; Pedrini, Denise

    2013-08-01

    To evaluate the effect of the addition of sodium trimetaphosphate (TMP) with or without fluoride on enamel demineralization, and the hardness and release of fluoride and TMP of resin composites. Bovine enamel slabs (4 x 3 x 3 mm) were prepared and selected based on initial surface hardness (n = 96). Eight experimental resin composites were formulated, according to the combination of TMP and sodium fluoride (NaF): TMP/NaF-free (control), 1.6% sodium fluoride (NaF), and 1.5%, 14.1% and 36.8% TMP with and without 1.6% NaF. Resin composite specimens (n = 24) were attached to the enamel slabs with wax and the sets were subjected to pH cycling. Next, surface and cross-sectional hardness and fluoride content of enamel as well as fluoride and TMP release and hardness of the materials were evaluated. Data were statistically analyzed using ANOVA (P composites (P > 0.05), but higher than in the other materials (P < 0.05). The combination of 14.1% TMP and fluoride resulted in less demineralization, especially on lesion surface (P < 0.05). The presence of TMP increased fluoride release from the materials and reduced their hardness.

  5. Fluoride Varnishes--Is There a Correlation Between Fluoride Release and Deposition on Enamel?

    Science.gov (United States)

    Bolis, Carlo; Härtli, Gian Peider; Lendenmann, Urs

    2015-01-01

    Fluoride uptake of enamel after application of fluoride varnishes was compared with fluoride release into artificial saliva. The hypothesis was that fluoride uptake is higher for products exhibiting faster fluoride release. Fluoride varnishes, i.e. Fluor Protector S, Duraphat, MI Varnish, Clinpro White Varnish, Profluorid Varnish and Enamel Pro Varnish were applied on bovine enamel specimens. Subsequently, specimens were incubated in artificial saliva. After removal of the varnishes, surface bound fluoride was extracted with potassium hydroxide and measured with an ion-selective electrode. Structurally bound fluoride was etched from the same specimens with perchloric acid. Fluoride release of varnish films into artificial saliva was measured for comparison. After 4 h in artificial saliva, the highest total enamel fluoride uptake of 47.9 μg F·cm-² was found with Fluor Protector S, followed by Enamel Pro Varnish with 22.1 μg F·cm-². The other products ranged between 12-16 μg F·cm-². This was several times higher than the negative control. Fluoride uptake did not correlate with release into artificial saliva. During the first 4 h, Duraphat released the lowest and MI Varnish the highest amount of fluoride with 7.7 and 249 μg F·cm-², respectively. The fluoride uptake of these two products was not statistically different. Enamel fluoride uptake cannot be predicted from the fluoride release rate of a product. Hence, based on the results of this study, fluoride release into artificial saliva is no measure for the efficacy of a fluoride varnish.

  6. A simple structural hydrazide-based gelator as a fluoride ion colorimetric sensor.

    Science.gov (United States)

    Bai, Binglian; Ma, Jie; Wei, Jue; Song, Jianxi; Wang, Haitao; Li, Min

    2014-06-01

    A 4-nitrobenzohydrazide derivative, N-(3,4,5-octyloxybenzoyl)-N'-(4'-nitrobenzoyl)hydrazine (C8), was synthesized. It could form stable gels in some of the tested organic solvents. The wide-angle X-ray diffraction analysis showed that the xerogels exhibited a layered structure. SEM images revealed that the molecules self-assembled into fibrous aggregates in the xerogels. FT-IR studies confirmed that the intermolecular hydrogen bonding between C=O and N-H groups was the major driving force for the formation of self-assembling gel processes. The gel is utilized for a 'naked eye' detection of fluoride ions, through a reversible gel-sol transition, which is associated with a color change from colorless to red. An extended conjugated system formed through the phenyl group and a five-membered ring based on intramolecular hydrogen bonding between the oxygen atom near the deprotonation nitrogen atom and the other NH, which is responsible for the dramatic color change upon addition of fluoride ions.

  7. Fluoride Content in Alcoholic Drinks.

    Science.gov (United States)

    Goschorska, Marta; Gutowska, Izabela; Baranowska-Bosiacka, Irena; Rać, Monika Ewa; Chlubek, Dariusz

    2016-06-01

    The aim of the study was to determine the role of alcoholic drinks as a potential source of dietary fluoride by means of measuring fluoride levels in selected alcoholic drinks available on the Polish market that are also diverse in terms of the percentage content of ethanol. The study was conducted on 48 types of drinks with low, medium, and high alcohol content available on the Polish market and offered by various manufacturers, both Polish and foreign. Fluoride concentrations in individual samples were measured by potentiometric method with a fluoride ion-selective electrode. The highest fluoride levels were determined in the lowest percentage drinks (less than 10 % v/v ethanol), with the lowest fluoride levels observed in the highest percentage drinks (above 40 % v/v ethanol). In terms of types of alcoholic drinks, the highest fluoride levels were determined in beers and wines, while the lowest levels were observed in vodkas. These data confirm the fact that alcoholic beverages need to be considered as a significant source of fluoride delivered into the body.

  8. Polydopamine coated electrospun poly(vinyldiene fluoride) nanofibrous membrane as separator for lithium-ion batteries

    Science.gov (United States)

    Cao, Chengying; Tan, Lei; Liu, Weiwei; Ma, Jiquan; Li, Lei

    2014-02-01

    In this study, polydopamine (PDA) coated electrospun poly(vinyldiene fluoride) (PVDF) nanofibrous membranes used as separator for lithium-ion batteries are successfully prepared. Their morphology, chemical and electrochemical characterization are investigated. The morphology and porosity measurements of the membranes show that the PDA coating does not harm to the structure of the electrospun PVDF nanofibrous membranes. Due to the PDA coating, it makes the PVDF surface hydrophilic and thus increases the electrolyte uptake and ionic conductivity, resulting in the enhanced performance of batteries. The battery using the PDA coated PVDF nanofibrous separator exhibits better cycling performance and higher power capability than that the battery using the bare PVDF nanofibrous separator. This study underlines that the PDA-coating treatment provides a promising process for the fabrication of advanced electrospun nanofibers separator in the lithium-ion battery applications.

  9. Stabilization of Th 3+ ions into mixed-valence thorium fluoride

    Science.gov (United States)

    Dubois, Marc; Dieudonné, Belto; Mesbah, Adel; Bonnet, Pierre; El-Ghozzi, Malika; Renaudin, Guillaume; Avignant, Daniel

    2011-01-01

    The unusual oxidation state +3 of the thorium has been stabilized into a lithium containing non-stoichiometric mixed-valence (III/IV) thorium fluorinated phase with formula Li 2+ xTh 12F 50 (0afore mentioned single phase may be considered as an insertion compound. The Li + insertion is accompanied by the simultaneous reduction of a part of the Th 4+ ions, resulting in a mixed-valence III/IV thorium fluoride. The electrochemical insertion of Li + ions into the open channels of the host matrix has been carried out at 60 °C, using an alkylcarbonate PC-LiClO 4 1 M electrolyte. The Li + and Th 3+ contents, both in the starting composition and the Li + inserted ones, were investigated by high resolution solid state 7Li NMR and EPR, respectively.

  10. Perchlorate Selectivity of Anion Exchange Resins as Evaluated Using Ion-Selective Electrodes.

    Science.gov (United States)

    Yamamoto, Kenji; Mitsuda, Shin'ya; Ohtake, Naomi; Murashige, Natsuki; Ohmuro, Satoshi; Yuchi, Akio

    2017-01-01

    The selectivity coefficients reported for perchlorate of the high selectivity on anion exchange resins (AXRs) have not been consistent with one another. Possible errors by the unique use of four parameters (concentrations of two anions in two phases) were experimentally verified. The concentrations of perchlorate buffered at low levels (10(-6) - 10(-4) mol L(-1)) by two forms of AXRs were successfully determined by potentiometry with a perchlorate ion-selective electrode. This gave reasonable coefficients. The coefficients for perchlorate on several AXRs were independent of the relative exchange (RE), in contrast to the previous reports. On the other hand, the coefficients for fluoride of the low selectivity that were examined for comparison decreased with an increase in RE, and the dependency was more remarkable for the resins of large exchange capacity.

  11. Synthesis of hydroxyapatite/multi-walled carbon nanotubes for the removal of fluoride ions from solution

    Science.gov (United States)

    Ruan, Zhongyuan; Tian, Yaxi; Ruan, Jifu; Cui, Guijia; Iqbal, Kanwal; Iqbal, Anam; Ye, Herui; Yang, Zhangzhong; Yan, Shiqiang

    2017-08-01

    A novel composite material, hydroxyapatite (HA)-multi-walled carbon nanotubes (MWCNTs), was prepared using a simple in-situ sol-gel method, and was used for the first time to remove fluoride from water. The novel HA-MWCNTs were characterized using TEM, FT-IR, BET and XRD analysis. The TEM and SAED results revealed that the MWCNTs were uniformly encapsulated by hydroxyapatite nanoparticles. The synthesized HA-MWCNTs had a high specific surface area (180.504 m2 g-1), with an average pore width (14.607 nm) and pore volume (0.774 cm3 g-1), which produced a defluoridation capacity (DC) of 30.22 mgF- g-1. This value was greater than unmodified hydroxyapatite (HA), which exhibited a larger specific surface area (172.233 m2 g-1) and an excellent DC of 17.80 mgF- g-1. A number of pertinent parameters that could affect the defluoridation performance of the HA/MWCNTs including weight ratios of the two key materials, solution pH and competing anions were carefully and comprehensively examined. It was found that the adsorption results followed the Langmuir and Freundlich isotherm model, and the sorption kinetics of the F- appeared to exhibit a pseudo second order. Moreover, the adsorption reaction was spontaneous and endothermic and appeared to exhibit a higher initial adsorption rate. This reaction appeared to occur result from both anion exchange and electrostatic interactions. When the HA-MWCNTs (MH6) were at an adsorbent dose of 2.0 g L-1, they were able to decrease the fluoride concentration of actual nuclear industry wastewater from 8.79 mg L-1 to about 0.25 mg L-1 (97.15% removal efficiency). The experimental results of this study showed that the HA-MWCNTs composites have application potential for the removal of fluoride ions from wastewater.

  12. DETERMINATION OF FLUORIDE IN HIGHLY SALINATED WATERS BY ION CHROMATOGRAPHY METHOD WITH USE OF SOLID PHASE EXTRACTION FOR SAMPLE PREPARATION

    Directory of Open Access Journals (Sweden)

    Beata Kostka

    2014-10-01

    Full Text Available Solid phase extraction (SPE is one of the most popular methods of matrix elimination in determination of anions by ion chromatography. Possibility of using cartridges containing a cation-exchange resin in the Ag+ and Na+ forms for determination of fluoride in the presence of very high concentration of chloride in mine waters was described in this paper. A Dionex ICS-2500 ion chromatograph was used for separation of anions in gradient elution using IonPac AS19 (4x250 mm separation column along with generated KOH eluent. Fluoride after separation was determined by conductivity detector with suppression. The investigations performed on mine waters (conductivity in the range 12 700 μS/cm–155 000 μS/cm and synthetic brine (38 820 mg/L Cl- and 3 408 mg/L SO4 2- confirmed usefulness of cartridges containing a cation-exchange resin for minimizing matrix influence on results of fluoride determination. The ion chromatography method accompanied by solid phase extraction for sample preparation proved to be very useful for determination of fluoride in highly salinated waters (i.e. mine waters because of low detection limit (0,02 mg/L, good precision (< 2,5 % and accuracy (recovery 91 % – 104 %.

  13. Fluorescent Sensing of Fluoride in Cellular System

    Science.gov (United States)

    Jiao, Yang; Zhu, Baocun; Chen, Jihua; Duan, Xiaohong

    2015-01-01

    Fluoride ions have the important roles in a lot of physiological activities related with biological and medical system, such as water fluoridation, caries treatment, and bone disease treatment. Great efforts have been made to develop new methods and strategies for F- detection in the past decades. Traditional methods for the detection of F- including ion chromatography, ion-selective electrodes, and spectroscopic techniques have the limitations in the biomedicine research. The fluorescent probes for F- are very promising that overcome some drawbacks of traditional fluoride detection methods. These probes exhibit high selectivity, high sensitivity as well as quick response to the detection of fluoride anions. The review commences with a brief description of photophysical mechanisms for fluorescent probes for fluoride, including photo induced electron transfer (PET), intramolecular charge transfer (ICT), fluorescence resonance energy transfer (FRET), and excited-state intramolecular proton transfer (ESIPT). Followed by a discussion about common dyes for fluorescent fluoride probes, such as anthracene, naphalimide, pyrene, BODIPY, fluorescein, rhodamine, resorufin, coumarin, cyanine, and near-infrared (NIR) dyes. We divide the fluorescent probes for fluoride in cellular application systems into nine groups, for example, type of hydrogen bonds, type of cleavage of Si-O bonds, type of Si-O bond cleavage and cylization reactions, etc. We also review the recent reported carriers in the delivery of fluorescent fluoride probes. Seventy-four typical fluorescent fluoride probes are listed and compared in detail, including quantum yield, reaction medium, excitation and emission wavelengths, linear detection range, selectivity for F-, mechanism, and analytical applications. Finally, we discuss the future challenges of the application of fluorescent fluoride probes in cellular system and in vivo. We wish that more and more excellent fluorescent fluoride probes will be developed

  14. Determination of glucose using a coupled-enzymatic reaction with new fluoride selective optical sensing polymeric film coated in microtiter plate wells.

    Science.gov (United States)

    Abd-Rabboh, Hisham S M; Meyerhoff, Mark E

    2007-05-15

    The determination of glucose in beverages is demonstrated using newly developed fluoride selective optical sensing polymeric film that contains aluminum (III) octaethylporphyrin (Al[OEP]) ionophore and the chromoionophore ETH7075 cast at the bottom of wells of a 96-well polypropylene microtiter plate. The method uses a dual enzymatic reaction involving glucose oxidase enzyme (GOD) and horseradish peroxidase (HRP), along with an organofluoro-substrate (4-fluorophenol) as the source of fluoride ions. The concentration of fluoride ions after enzymatic reaction is directly proportional to the glucose level in the sample. The method has a detection limit of 0.8 mmol L(-1), a linear range of 0.9- 40 mmol L(-1) and a sensitivity of 0.125 absorbance unit/decade of glucose concentration. Glucose levels in several beverage samples determined using the proposed method correlate well with a reference spectrophotometric enzyme method based on detection of hydrogen peroxide using bromopyrogallol red dye (BPR). The new method can also be used to determine H(2)O(2) concentrations in the 0.1 - 50 mmol L(-1) range using a single enzymatic reaction involving H(2)O(2) oxidation of 4-fluorophenol catalyzed by HRP. The methodology could potentially be used to detect a wide range of substrates for which selective oxidase enzymes exist (to generate H(2)O(2)), with the high throughput of simple microtiter plate detection scheme.

  15. Calix[4]pyrrole derivative: recognition of fluoride and mercury ions and extracting properties of the receptor-based new material.

    Science.gov (United States)

    de Namor, Angela F Danil; Khalife, Rasha

    2008-12-11

    A calix[4]pyrrole derivative, namely, meso-tetramethyl tetrakis (4-phenoxy methyl ketone) calix[4]pyrrole, 1, was synthesized and structurally (1H NMR) and thermodynamically characterized. The complexing properties of this receptor with a wide variety of anions and cations in dipolar aprotic media (acetonitrile, propylene carbonate, and dimethyl sulfoxide) were investigated through 1H NMR and conductance studies. The former technique was used to assess whether or not complexation occurs and if so to identify the active sites of interaction of 1 with ions. The composition of the complexes was established by conductance measurements. It was found that in dipolar aprotic solvents, 1 interacts only with two polluting ions (fluoride and mercury). The complexation thermodynamics of 1 and these ions in these solvents is reported. The medium effect on the binding process involving the fluoride ion is discussed taking into account the solvation properties of reactants and the product. Complexes of moderate stability are found. Given that this is an important factor to consider for the recycling of the loaded material in extraction processes, 1 was treated with formaldehyde in basic medium leading to the production of a calix[4]pyrrole based material able to extract fluoride and mercury (II) ions from water. Thus the optimum conditions for the extraction of these ions from aqueous solutions were established. The material is easily recyclable using an organic acid. Final conclusions are given.

  16. Analysis of 1-Minute Potentially Available Fluoride from Dentifrice

    Science.gov (United States)

    Carey, Clifton M; Holahan, Erin C; Schmuck, Burton D

    2014-01-01

    Previous reports found that some fluoride-containing dentifrices do not release effective concentrations of fluoride during brushing. Failure to release fluoride can be due to dentifrice matrix components that interfere with the solubilization of the fluoride salts during brushing. A new generation of dentifrices has the capability to precipitate beneficial fluoride salts during tooth brushing. Therefore, a method that assesses the potentially available fluoride during the 1-minute brushing is needed. A new filter-paper absorption method to assess the 1-min bioavailable fluoride concentration was developed to meet this need. This method utilizes coiled filter paper that rapidly absorbs the aqueous phase of the dentifrice slurry followed by centrifugation to recover that fluid for fluoride measurement via fluoride ion-selective electrode. The analytical method was used to successfully determine the total fluoride and 1-min bioavailable fluoride in eight dentifrice products containing sodium fluoride (NaF), disodium monofluorophosphate (Na2FPO3, MFP), stannous fluoride (SnF2), or NaF with amorphous calcium phosphate (NaF + ACP). The results showed that some of the dentifrices tested had significantly lower potentially available fluoride than the total fluoride. For a MFP-containing sample, aged seven years past its expiry date, there was significant reduction in the bioavailable fluoride compared to MFP products that were not aged. Other than the aged MFP and the SnF2-containing samples the bioavailable fluoride for all products tested had at least 80 % of the label fluoride concentration. The filter paper absorption method yielded reproducible results for the products tested with MFP samples showing the largest variations. PMID:25821392

  17. Fluoride ions sorption of the water using natural and modified hematite with aluminium hydroxide; Sorcion de iones fluoruro del agua utilizando hematita natural y hematita acondicionada con hidroxido de aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Teutli S, E. A.

    2011-07-01

    Fluorine is a mineral known for its dental benefits, but fluoride ions can cause fluoro sis in excessive quantities. There are many epidemiological studies on possible adverse effects resulting from prolonged ingestion of fluoride through drinking water. These studies demonstrate that fluoride mainly affects the bone tissue (bones and teeth), may produce an adverse effect on tooth enamel and can cause mild dental fluoro sis at concentrations from 0.9 to 1.2 mg/L in drinking water. In several states of Mexico, water contaminated with fluoride ions can be found, such as Aguascalientes, Chihuahua, Coahuila, Durango, Guanajuato, Sonora, Zacatecas, San Luis Potosi and Jalisco, where the fluoride ions levels are higher than 1.5 mg/L, established by the Mexican Official Standard (NOM-127-Ssa-2000) which sets the permissible limits of water for human use and consumption. Currently, several technologies have been proposed to remove fluoride ions from water such as precipitation methods which are based on the addition of chemicals to water and sorption methods to removed fluoride ions by sorption or ion exchange reactions by some suitable substrate capable of regenerate and reuse. In this work, the sorption of fluoride ions using unmodified and modified hematite with aluminum hydroxide to remove fluoride ions from water by bath experiments was studied. The hematite was modified by treating it with aluminum hydroxide, NaOH and Al{sub 2}(SO{sub 4}){sub 3} solutions. The characterization of hematite before and after modification with aluminum hydroxide was studied by X-ray diffraction, scanning electron microscopy, EDS and Bet. The effect of ph, contact time, concentration of fluoride ions, and the dose of sorbent on the sorption of fluoride ions by the modified hematite were studied. Equilibrium was reached within 48 hours of contact time and the maximum sorption of fluoride ions were in the range pH{sub eq} between 2.3 and 6.2. Sorption capacities of fluoride ions as a

  18. A reversible and reusable selective chemosensor for fluoride detection using a phenolic OH-containing BODIPY dye by both colorimetric 'naked-eye' and fluorometric modes.

    Science.gov (United States)

    Wang, Lingyun; Fang, Guipo; Cao, Derong

    2014-11-01

    A novel BODIPY-based probe 1 was designed and synthesized as a selective fluorescent and colorimetric chemosensor for fluoride. The spectral responses of 1 to fluoride in acetonitrile were studied: an approximately 118 nm red shift in absorption and 'turn-off' emission response was observed. The striking pink to indigo change in ambient light was thought to be due to the deprotonation of the phenol moiety by way of O-H · · · F hydrogen bonding interactions. Interestingly, when the nonfluorescent 1-F(-) solution treated with trifluoroacetic acid (TFA) resulted in color change from indigo to pink and a significant enhancement of fluorescence intensity (10-fold). Furthermore, the reversibility and reusability of probe 1 for the detection of F(-) ion was tested for four cycles indicating the probe 1 could be used in reversible manner.

  19. Dynamic behavior of ion-selective electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Pungor, E.; Linder, E.; Toth, K.

    1988-01-01

    This book provides a survey of the different techniques employed to study time-dependent processes of ion-selective electrodes. The fundamentals, the impedance field, the polarization field, and the activity step methods are treated in depth with emphasis on the information content of the results provided by the different techniques relevant to the dynamic characteristics of ion-selective electrodes. Within the activity step methods the different theoretical models derived to describe the potential-time function of ion-selective electrodes are critically discussed.

  20. Alimentary fluoride intake in preschool children

    Science.gov (United States)

    2011-01-01

    Background The knowledge of background alimentary fluoride intake in preschool children is of utmost importance for introducing optimal and safe caries preventive measures for both individuals and communities. The aim of this study was to assess the daily fluoride intake analyzing duplicate samples of food and beverages. An attempt was made to calculate the daily intake of fluoride from food and swallowed toothpaste. Methods Daily alimentary fluoride intake was measured in a group of 36 children with an average age of 4.75 years and an average weight of 20.69 kg at baseline, by means of a double plate method. This was repeated after six months. Parents recorded their child's diet over 24 hours and collected duplicated portions of food and beverages received by children during this period. Pooled samples of food and beverages were weighed and solid food samples were homogenized. Fluoride was quantitatively extracted from solid food samples by a microdiffusion method using hexadecyldisiloxane and perchloric acid. The content of fluoride extracted from solid food samples, as well as fluoride in beverages, was measured potentiometrically by means of a fluoride ion selective electrode. Results Average daily fluoride intake at baseline was 0.389 (SD 0.054) mg per day. Six months later it was 0.378 (SD 0.084) mg per day which represents 0.020 (SD 0.010) and 0.018 (SD 0.008) mg of fluoride respectively calculated per kg bw/day. When adding the values of unwanted fluoride intake from the toothpaste shown in the literature (0.17-1.21 mg per day) the estimate of the total daily intake of fluoride amounted to 0.554-1.594 mg/day and recalculated to the child's body weight to 0.027-0.077 mg/kg bw/day. Conclusions In the children studied, observed daily fluoride intake reached the threshold for safe fluoride intake. When adding the potential fluoride intake from swallowed toothpaste, alimentary intake reached the optimum range for daily fluoride intake. These results showed that

  1. Electrospun montmorillonite modified poly(vinylidene fluoride) nanocomposite separators for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Changjiang; Yang, Shuli; Zhao, Xinfei [College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Du, Pingfan, E-mail: dupf@zstu.edu.cn [College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Ministry of Education), Zhejiang Sci-Tech University, Hangzhou 310018 (China); Xiong, Jie, E-mail: jxiong@zstu.edu.cn [College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Ministry of Education), Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2016-07-15

    Highlights: • Composite separators of PVDF and MMT for lithium-ion batteries were electrospun. • Thermal dimensional stability and tensile property of composite separators get improved. • Presence of montmorillonite promotes electrical properties of PVDF fibrous separators. • Batteries consisting of PVDF/MMT-5% separator achieve the best performance. - Abstract: Composite separators of poly(vinylidene fluoride) (PVDF) with different contents of montmorillonite (MMT) for Li-ion batteries have been fabricated by electrospinning. The morphology, function group, crystallinity, and mechanical properties of membranes were investigated by scanning electron microscope (SEM), Fourier Transform infrared spectra (FT-IR), differential scanning calorimetry (DSC), and tensile test, respectively. Interlayer spacing of MMT in polymer was characterized by X-ray diffraction (XRD). In addition, the results of electrochemical measurements suggest that PVDF/MMT-5% composite membrane has maximum ionic conductivity of 4.2 mS cm{sup −1}, minimum interfacial resistance of 97 Ω, and excellent electrochemical stability. The cell comprising PVDF/MMT-5% composite membrane shows higher capacity and more stable cycle performance than the one using commercial Celgard PP membrane.

  2. Fluoride in Dental Biofilm Varies across Intra-Oral Regions

    DEFF Research Database (Denmark)

    Staun, Line; Baelum, Vibeke; Tenuta, Livia Maria Andaló

    2017-01-01

    Information on differences in biofilm fluoride concentration across intra-oral regions may help explain the distribution of caries within the dentition. The aim of this cross-sectional study was to describe the fluoride concentration in saliva and in biofilm fluid and biofilm solids across 6 intra......-oral regions. Unstimulated whole saliva was collected from 42 participants and biofilm harvested from the buccal sites in the 4 molar and 2 anterior regions. Samples were collected at least 1 h after use of fluoride dentifrice. No attempt was made to control the participants' food consumption or use of other...... topical agents. Centrifuged saliva, biofilm fluid, and biofilm solids were analysed for fluoride using a fluoride ion-selective electrode, adapted for microanalysis. Fluoride in biofilm varied across intra-oral regions. The mean biofilm fluid fluoride concentrations across the oral cavity ranged from 11...

  3. Determination of Free Fluoride in Toothpaste by Ion Chromatography%离子色谱法测定牙膏中游离氟

    Institute of Scientific and Technical Information of China (English)

    钟志雄; 杜达安; 梁旭霞

    2001-01-01

    为研究离子色谱法测定牙膏样品氟,采用NaHCO3和Na2B4O7-NaOH作淋洗液分别进行测定,优化色谱条件,选用0.45~1.0 mmol/LNaHCO3和5.0~20.0 mmol/L NaB4O7-1.0~2.0 mmol/L NaOH作淋洗液都能有效地把氟与乙酸盐、甲酸盐峰分离,并能准确定量分析。样品的加标回收率为92.5%~100.2%,RSD<0.6%,检出限小于0.208 mg/kg。同时与离子选择电极法作对比测定,结果表明以NaHCO3为淋洗液氟的测定值与之较为接近。%To determine fluoride in toothpaste samples by ion chromatography,the solution of NaHCO3 and the solution of Na2B4O7-NaOH were selected as eluents respectively to optimize chromatographic detection conditions. Either the 0. 45~1.0 mmol/L NaHCO3 solution or the 5.0~20. 0 mmol/L NaB4O7-1. 0~2.0 mmol/L NaOH solution as eluents could effectively separate the chromatographic peak of fluoride in toothpaste samples from acetate and formate and accurately quantify the contents of fluoride in toothpaste samples. The recovery rates,precision(relative standard deviation) and detection limit were 92.5%~100. 2% ,<0. 6% and 0. 208 mg/kg respectively. The data obtained by ion chromatography using NaHCO3 solution as eluent more approached to that by selective-fluoride-ion-electrode.

  4. Colorimetric determination of the fluoride ion - application to uranium metal and to uranous fluoride; Dosage colorimetrique de l'ion fluor - application a l'uranium metal et au fluorure uraneux

    Energy Technology Data Exchange (ETDEWEB)

    Hering, H.; Hure, J.; Legrand, S. [Commissariat a l' Energie Atomique (France)

    1949-12-01

    In the determination described for fluoride in U metal, the U is brought into H{sub 2}SO{sub 4} solution by anodic oxidation, the fluo-silicic acid is distilled by entrainment in water vapor, and the F ion is determined in the distillate by using the fact that it complexes Zr and thus prevents the formation of the Zr-alizarin S lake. For F ion in UF{sub 4}, the compound is dissolved in a Na{sub 2}CO{sub 3}-H{sub 2}O{sub 2} mixture, and F is determined in the solution by the colorimetric method described. (author)

  5. A novel fluoride-selective electrode based on metalloporphyrin grafted-grapheneoxide.

    Science.gov (United States)

    Poursaberi, T; Ganjali, M R; Hassanisadi, M

    2012-11-15

    In this work, the unique properties of graphene oxide were combined with the anion selectivity of metalloporphyrin to fabricate a novel fluoride-selective sensor. The electrode made of 27% PVC, 54% NPOE, 4% NaTPB and 15% NbTPP-GO was found to show the most favorable behavior. The sensor shows a Nernstian response (58.3 mV decade(-1)) in the concentration window of 5.0×10(-1)-5.0×10(-7) mol L(-1)with detection limit of 8.0×10(-87) mol L(-1). The response of the sensor was found to be stable in the pH range of 3.0-7.0 and the metalloporphyrin grafted-GO based F(-) sensors displayed very good selectivity with respect to a number of anions. The proposed sensor displays a long life time (more than 12 weeks) with a short response time of about 20 s.

  6. The Advantages of the Use of Ion- Selective Potentiometry in Relation to UV/VIS Spectroscopy

    Directory of Open Access Journals (Sweden)

    Amra Bratovčić

    2009-12-01

    Full Text Available Electro analytical methods have a long history of development. Ion-selective potentiometry is one of the electro analytical methods. There are some advantages of the use of Ion selective potentiometry (ISP which is accurate, fast, economic and sensitive in relation to the standard method, UV/VIS spectroscopy. The development of potentiometric ion-selective electrodes is a very interesting field because it has a wide range of applications in determining ions in water and other mediums. The use of ion-selective electrodes enables the determination of ion species in a trace. Ion-selective electrodes are suitable for analysis in industry, for control processes, for physiological measurements and environmental monitoring. In recent years it was used for the determination of many ions in the food industry such as determination of calcium in milk products, fruit juice and different kinds of vegetables. In our experiment measurement of bottled water using ISP showed lower level of fluoride compared to measurement by UV/ VIS spectroscopy. This results confirmed higher sensitivity of ISE in reference to UV/VIS spectroscopy. By our experimental data we can conclude that the concentration in examined sample was within the allowed concentration according to World Health Organisation

  7. A preliminary investigation of lithogenic and anthropogenic influence over fluoride ion chemistry in the groundwater of the southern coastal city, Tamilnadu, India.

    Science.gov (United States)

    Selvam, S

    2015-03-01

    A total of 72 groundwater samples were collected from open wells and boreholes during pre- and post-monsoon periods in Tuticorin. Samples were analyzed for physicochemical properties, major cations, and anions in the laboratory using the standard methods given by the American Public Health Association. The fluoride concentration was analyzed in the laboratory using Metrohm 861 advanced compact ion chromatography. The geographic information system-based spatial distribution map of different major elements has been prepared using ArcGIS 9.3. The fluoride concentration ranges between 0.16 mg/l and 4.8 mg/l during pre-monsoon and 0.2-3.2 mg/l during post-monsoon. Alkaline pH, low calcium concentrations, high groundwater temperatures, and semiarid climatic conditions of the study area may cause elevated fluoride concentrations in groundwater, by increasing the solubility of fluoride-bearing formations (fluoride). Linear trend analysis on seasonal and annual basis clearly depicted that fluoride pollution in the study area is increasing significantly. Fluoride concentrations showed positive correlations with those of Na(+) and HCO3 (-) and negative correlations with Ca(2+) and Mg(2+). The alkaline waters were saturated with calcite in spite of the low Ca(2+) concentrations. Northwestern parts of the study area are inherently enriched with fluorides threatening several ecosystems. The saturation index indicates that dissolution and precipitation contribute fluoride dissolution along with mixing apart from anthropogenic activities.

  8. In vitro reconstituted biotransformation of 4-fluorothreonine from fluoride ion: application of the fluorinase.

    Science.gov (United States)

    Deng, Hai; Cross, Stuart M; McGlinchey, Ryan P; Hamilton, John T G; O'Hagan, David

    2008-12-22

    In this paper, we report that fluoride ion is converted to the amino acid/antibiotic 4-fluorothreonine 2 in a biotransformation involving five (steps a-e) overexpressed enzymes. The biotransformation validates the biosynthetic pathway to 4-fluorothreonine in the bacterium Streptomyces cattleya (Schaffrath et al., 2002). To achieve an in vitro biotransformation, the fluorinase and the purine nucleoside phosphorylase (PNP) enzymes (steps a and b), which are coded for by the flA and flB genes of the fluorometabolite gene cluster in S. cattleya, were overexpressed. Also, an isomerase gene product that can convert 5-FDRP 6 to 5-FDRibulP 7 (step c) was identified in S. cattleya, and the enzyme was overexpressed for the biotransformation. A fuculose aldolase gene from S. coelicolor was overexpressed in E. coli and was used as a surrogate aldolase (step d) in these experiments. To complete the complement of enzymes, an ORF coding the PLP-dependent transaldolase, the final enzyme of the fluorometabolite pathway, was identified in genomic DNA by a reverse genetics approach, and the S. cattleya gene/enzyme was then overexpressed in S. lividans. This latter enzyme is an unusual PLP-dependent catalyst with some homology to both bacterial serine hydroxymethyl transferases (SHMT) and C5 sugar isomerases/epimerases. The biotransformation demonstrates the power of the fluorinase to initiate C-F bond formation for organo-fluorine synthesis.

  9. Conversion Reaction Mechanisms in Lithium Ion Batteries: Study of the Binary Metal Fluoride Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Feng; Robert, Rosa; Chernova, Natasha A.; Pereira, Nathalie; Omenya, Fredrick; Badway, Fadwa; Hua, Xiao; Ruotolo, Michael; Zhang, Ruigang; Wu, Lijun; Volkov, Vyacheslav; Su, Dong; Key, Baris; Whittingham, M. Stanley; Grey, Clare P.; Amatucci, Glenn G.; Zhu, Yimei; Graetz, Jason (Binghamton); (Rutgers); (BNL); (Cambridge); (SBU)

    2015-10-15

    Materials that undergo a conversion reaction with lithium (e.g., metal fluorides MF{sub 2}: M = Fe, Cu, ...) often accommodate more than one Li atom per transition-metal cation, and are promising candidates for high-capacity cathodes for lithium ion batteries. However, little is known about the mechanisms involved in the conversion process, the origins of the large polarization during electrochemical cycling, and why some materials are reversible (e.g., FeF{sub 2}) while others are not (e.g., CuF{sub 2}). In this study, we investigated the conversion reaction of binary metal fluorides, FeF{sub 2} and CuF{sub 2}, using a series of local and bulk probes to better understand the mechanisms underlying their contrasting electrochemical behavior. X-ray pair-distribution-function and magnetization measurements were used to determine changes in short-range ordering, particle size and microstructure, while high-resolution transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) were used to measure the atomic-level structure of individual particles and map the phase distribution in the initial and fully lithiated electrodes. Both FeF{sub 2} and CuF{sub 2} react with lithium via a direct conversion process with no intercalation step, but there are differences in the conversion process and final phase distribution. During the reaction of Li{sup +} with FeF{sub 2}, small metallic iron nanoparticles (<5 nm in diameter) nucleate in close proximity to the converted LiF phase, as a result of the low diffusivity of iron. The iron nanoparticles are interconnected and form a bicontinuous network, which provides a pathway for local electron transport through the insulating LiF phase. In addition, the massive interface formed between nanoscale solid phases provides a pathway for ionic transport during the conversion process. These results offer the first experimental evidence explaining the origins of the high lithium reversibility in FeF{sub 2}. In contrast

  10. Fluoride intake from fluids and urinary fluoride excretion by young children in Kuwait: a non-fluoridated community.

    Science.gov (United States)

    Akpata, Enosakhare S; Behbehani, Jawad; Akbar, Jaber; Thalib, Lukman; Mojiminiyi, Olusegun

    2014-06-01

    To determine the pattern of fluid consumption, fluoride intake from the fluids and urinary fluoride excretion by children aged 1-9 years in Kuwait, a nonfluoridated community. Using the cluster sampling technique, children aged 1-9 years were chosen from 2000 randomly selected households in Kuwait. Questionnaires were then administered to their mothers to determine the children's daily fluid intake. Fluoride concentrations in tap water as well as all brands of bottled water and beverages consumed by the children were measured, using the fluoride ion-specific electrode. Fluoride excretion was determined in 400 randomly selected children, based on fluoride/creatinine ratio. The mean daily fluid consumption by the children was high, being 1115-1545 ml. About 40% of the fluid intake was plain (tap and bottled) water and approximately 10% of the children drank bottled water exclusively. Fluoride concentration in tap water was low (0.04±SD 0.02 ppm), but was higher in bottled water (0.28±SD 0.40 ppm). Mean daily fluoride ingestion from fluids was 0.013-0.018 mg/kg body weight (bw). Even after allowing for fluoride ingestion from other sources, mean daily fluoride ingestion was still below 0.1 mg/kg bw set by the United States of America Institute of Medicine as the lowest-observed-adverse-effect level for moderate enamel fluorosis in children aged up to 8 years. Furthermore, the mean daily urinary fluoride excretion of 128-220 μg was below the provisional standard of 360-480 μg for optimal fluoride usage by children aged 3-5 years. Fluoride ingestion from fluids and urinary fluoride excretion by the children were below the recommendations for optimal fluoride usage. Thus, there is room for an upward adjustment of fluoride level in public drinking water supplies in Kuwait, as a caries preventive measure. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. New inorganic (an)ion exchangers with a higher affinity for arsenate and a competitive removal capacity towards fluoride, bromate, bromide, selenate, selenite, arsenite and borate

    KAUST Repository

    Chubar, Natalia

    2011-12-01

    Highly selective materials and effective technologies are needed to meet the increasingly stronger drinking water standards for targeted ionic species. Inorganic ion exchangers based on individual and mixed-metal hydrous oxides (or mixed adsorbents that contain inorganic ion exchangers in their composition) are adsorptive materials that are capable of lowering the concentrations of anionic contaminants, such as H 2AsO 4 -, H 3AsO 3, F -, Br -, BrO 3 -, HSeO 4 -, HSeO 3 - and H 3BO 3, to 10 μg/L or less. To achieve a higher selectivity towards arsenate, a new ion exchanger based on Mg-Al hydrous oxides was developed by a novel, cost-effective and environmentally friendly synthesis method via a non-traditional (alkoxide-free) sol-gel approach. The exceptional adsorptive capacity of the Mg-Al hydrous oxides towards H 2AsO 4 - (up to 200 mg[As]/gdw) is due to the high affinity of this sorbent towards arsenate (steep equilibrium isotherms) and its fast adsorption kinetics. Because of the mesoporous (as determined by N 2 adsorption and SEM) and layered (as determined by XRD and FTIR) structure of the ion-exchange material as well as the abundance of anion exchange sites (as determined by XPS and potentiometric titration) on its surface the material demonstrated very competitive (or very high) removal capacity towards other targeted anions, including fluoride, bromide, bromate, selenate, selenite, and borate. © 2011 IWA Publishing.

  12. Ion selectivity strategies of sodium channel selectivity filters.

    Science.gov (United States)

    Dudev, Todor; Lim, Carmay

    2014-12-16

    CONSPECTUS: Sodium ion channels selectively transport Na(+) cations across the cell membrane. These integral parts of the cell machinery are implicated in regulating the cardiac, skeletal and smooth muscle contraction, nerve impulses, salt and water homeostasis, as well as pain and taste perception. Their malfunction often results in various channelopathies of the heart, brain, skeletal muscles, and lung; thus, sodium channels are key drug targets for various disorders including cardiac arrhythmias, heart attack, stroke, migraine, epilepsy, pain, cancer, and autoimmune disorders. The ability of sodium channels to discriminate the native Na(+) among other competing ions in the surrounding fluids is crucial for proper cellular functions. The selectivity filter (SF), the narrowest part of the channel's open pore, lined with amino acid residues that specifically interact with the permeating ion, plays a major role in determining Na(+) selectivity. Different sodium channels have different SFs, which vary in the symmetry, number, charge, arrangement, and chemical type of the metal-ligating groups and pore size: epithelial/degenerin/acid-sensing ion channels have generally trimeric SFs lined with three conserved neutral serines and/or backbone carbonyls; eukaryotic sodium channels have EKEE, EEKE, DKEA, and DEKA SFs with an invariant positively charged lysine from the second or third domain; and bacterial voltage-gated sodium (Nav) channels exhibit symmetrical EEEE SFs, reminiscent of eukaryotic voltage-gated calcium channels. How do these different sodium channel SFs achieve high selectivity for Na(+) over its key rivals, K(+) and Ca(2+)? What factors govern the metal competition in these SFs and which of these factors are exploited to achieve Na(+) selectivity in the different sodium channel SFs? The free energies for replacing K(+) or Ca(2+) bound inside different model SFs with Na(+), evaluated by a combination of density functional theory and continuum dielectric

  13. β-Cyclodextrin and calix[4]arene-25,26,27,28-tetrol capped carbon dots for selective and sensitive detection of fluoride.

    Science.gov (United States)

    Baruah, Upama; Gogoi, Neelam; Majumdar, Gitanjali; Chowdhury, Devasish

    2015-03-06

    In this work we have designed a novel system based on carbon dots prepared from chitosan gel capped with β-cyclodextrin and calix[4]arene-25,26,27,28-tetrol for sensitive and selective detection of fluoride ions in aqueous media. Fluorescent carbon dots prepared from chitosan gel when capped with β-cyclodextrin and calix[4]arene-25,26,27,28-tetrol results in quenching of its fluorescence intensity. Introduction of F(-) ions to carbon dots capped with β-cyclodextrin and calix[4]arene-25,26,27,28-tetrol system results in enhancement and restoration of fluorescence intensity leading to detection of F(-) ion. Minimum detection limit was determined to be ∼6.6 μM. The detection is selective as with other halide ions i.e. Cl(-), Br(-) and I(-) and hydroxyl ion (OH(-)), there is observed decrease of fluorescence intensity. A possible mechanism to justify the observation is also discussed in the paper.

  14. Chemical proteomics with sulfonyl fluoride probes reveals selective labeling of functional tyrosines in glutathione transferases.

    Science.gov (United States)

    Gu, Christian; Shannon, D Alexander; Colby, Tom; Wang, Zheming; Shabab, Mohammed; Kumari, Selva; Villamor, Joji Grace; McLaughlin, Christopher J; Weerapana, Eranthie; Kaiser, Markus; Cravatt, Benjamin F; van der Hoorn, Renier A L

    2013-04-18

    Chemical probes have great potential for identifying functional residues in proteins in crude proteomes. Here we studied labeling sites of chemical probes based on sulfonyl fluorides (SFs) on plant and animal proteomes. Besides serine proteases and many other proteins, SF-based probes label Tyr residues in glutathione transferases (GSTs). The labeled GSTs represent four different GST classes that share less than 30% sequence identity. The targeted Tyr residues are located at similar positions in the promiscuous substrate binding site and are essential for GST function. The high selectivity of SF-based probes for functional Tyr residues in GSTs illustrates how these probes can be used for functional studies of GSTs and other proteins in crude proteomes.

  15. Corrosion investigations on zircaloy-4 and titanium dissolver materials for MOX fuel dissolution in concentrated nitric acid containing fluoride ions

    Science.gov (United States)

    Jayaraj, J.; Krishnaveni, P.; Krishna, D. Nanda Gopala; Mallika, C.; Mudali, U. Kamachi

    2016-05-01

    Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a dissolution catalyst in boiling nitric acid for an effective dissolution of the spent fuel. High corrosion rates were obtained for the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO3 + 0.05 M NaF. Complexing the fluoride ions either with Al(NO3)3 or ZrO(NO3)2 aided in decreasing the corrosion rates of Zr-4 and CP-Ti. From the obtained corrosion rates it is concluded that CP-Ti is a better dissolver material than Zr-4 for extended service life in boiling 11.5 M HNO3 + 0.05 M NaF, when complexed with 0.15 M ZrO(NO3)2. XPS analysis confirmed the presence of TiO2 and absence of fluoride on the surface of CP-Ti samples, indicating that effective complexation had occurred in solution leading to passivation of the metal and imparting high corrosion resistance.

  16. Cyclotron production of [18F]fluoride ion and [18F]fluorine gas and their medical applications

    Science.gov (United States)

    VanBrocklin, H. F.; O'Neil, J. P.

    1997-02-01

    One of the newest low energy cyclotrons for the production of positron emitting isotopes has been sited at Lawrence Berkeley National Laboratory. This prototype CTI RDS-111, proton only, 11 MeV, negative ion machine is capable of producing GBq quantities of fluorine-18 for radiopharmaceutical applications. A CTI designed target changing system developed for this cyclotron can hold up to eight small targets. We have tested two small high pressure CTI silver body target designs for the production of [18F]fluoride ion and compared them to the CTI RDS-112 style low pressure target. The high pressure target can produce up to 100% more activity for a given time and beam current with improved saturation yields. A high pressure aluminum RDS-112 gas target has been used to produce [18F]F2. The fluoride ion produced from this machine has been used to label fluorodeoxyglucose to trace glucose metabolism in patients and the fluorine gas has been used to label fluoro-meta-tyrosine to image therapeutic response to gene therapy in Parkinsonian monkeys.

  17. Origins of Large Voltage Hysteresis in High-Energy-Density Metal Fluoride Lithium-Ion Battery Conversion Electrodes.

    Science.gov (United States)

    Li, Linsen; Jacobs, Ryan; Gao, Peng; Gan, Liyang; Wang, Feng; Morgan, Dane; Jin, Song

    2016-03-02

    Metal fluorides and oxides can store multiple lithium ions through conversion chemistry to enable high-energy-density lithium-ion batteries. However, their practical applications have been hindered by an unusually large voltage hysteresis between charge and discharge voltage profiles and the consequent low-energy efficiency (hysteresis are rarely studied and poorly understood. Here we employ in situ X-ray absorption spectroscopy, transmission electron microscopy, density functional theory calculations, and galvanostatic intermittent titration technique to first correlate the voltage profile of iron fluoride (FeF3), a representative conversion electrode material, with evolution and spatial distribution of intermediate phases in the electrode. The results reveal that, contrary to conventional belief, the phase evolution in the electrode is symmetrical during discharge and charge. However, the spatial evolution of the electrochemically active phases, which is controlled by reaction kinetics, is different. We further propose that the voltage hysteresis in the FeF3 electrode is kinetic in nature. It is the result of ohmic voltage drop, reaction overpotential, and different spatial distributions of electrochemically active phases (i.e., compositional inhomogeneity). Therefore, the large hysteresis can be expected to be mitigated by rational design and optimization of material microstructure and electrode architecture to improve the energy efficiency of lithium-ion batteries based on conversion chemistry.

  18. Vibrational echo spectral observables and frequency fluctuations of hydration shell water around a fluoride ion from first principles simulations

    Indian Academy of Sciences (India)

    DEEPAK OJHA; AMALENDU CHANDRA

    2017-07-01

    Aqueous solution of a fluoride ion at 300K is studied using the method of ab initio molecular dynamics simulation. Instantaneous fluctuations in vibrational frequencies of local OD stretch modes of deuterated water are calculated using a time-series analysis of the simulated trajectory. The vibrational spectraldiffusion of OD modes in the first and second solvation shells and also in bulk of the aqueous fluoride ionic solution are studied through calculations of the frequency time correlation function (FTCF), joint probability distributions, slope of three pulse photon echo (S3PE) and two dimensional infrared spectrum (2D-IR). The vibrational spectral dynamics in the first solvation shell shows decay with three components which can be correlated with the dynamics of intact ion-water hydrogen bonds, ion-water hydrogen bond lifetime and the escape dynamics of water molecules from the solvation shell. The vibrational spectral diffusion of OD modes in the second solvation shell and in the bulk show very similar decay behavior. The timescales obtained from FTCF, S3PE and the slope of nodal line (SNL) of 2D-IR are found to be in reasonable agreement with each others.

  19. Comparative study of adsorbents for the removal of fluoride ions from water use and consumption in Mexico; Estudio comparativo de adsorbentes para la remocion de iones fluoruro del agua de uso y consumo en Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Teutli S, E. A.

    2014-07-01

    Although fluoride is essential for health many studies have shown it is associated with some health problems, such as fluoro sis, thyroid disorder, neurological disease, Alzheimer, pineal gland and cancer. One of the major routes of exposure is through drinking water. The World Health Organization (Who) allows only 1.5 mg/L as a safe limit for fluoride ions in drinking water and the EPA U. S. Environmental Protection Agency has recently proposed 0.7 mg/L. In some cases, the water extracted from deep wells has concentrations of fluoride ions above 1.5 mg/L (NOM-127-SSA1-2000) which is the permissible limit of water for human use and consumption (whuc). In several countries, there are high concentrations of fluoride ions due to the geological distribution of fluorine-rich rocks. In our country we can find several states that have concentrations higher than 1.5 mg/L of fluoride ions in water, such as Aguascalientes, Zacatecas, Chihuahua, Coahuila, Durango, Guanajuato, Sonora, Jalisco and San Luis Potosi. Various technologies have been proposed to remove fluoride ions from water, such as adsorption, ion exchange, reverse osmosis, nano filtration, electrodialysis, dialysis and electrocoagulation. Sorption is superior to other techniques in terms of initial cost, simplicity of design and ease of operation. In this work systematic studies were done considering the aspects mentioned above, in order to determine the adsorbents properties and most suitable conditions for the removal of fluoride ions from whuc. It is important to note that to date no adsorption treatments for the removal of fluoride ions from water for human use and consumption in our country is done, although there are established methodologies, they have not been implemented because of their high costs. In this work an integral study was done on the removal of fluoride ions from water for human use and consumption. A comparative study of hematite, calcite and zeolite as adsorbents was performed to develop a

  20. Corrosion investigations on zircaloy-4 and titanium dissolver materials for MOX fuel dissolution in concentrated nitric acid containing fluoride ions

    Energy Technology Data Exchange (ETDEWEB)

    Jayaraj, J.; Krishnaveni, P.; Krishna, D. Nanda Gopala; Mallika, C.; Mudali, U. Kamachi, E-mail: kamachi@igcar.gov.in

    2016-05-15

    Aqueous reprocessing of plutonium-rich mixed oxide fuels require fluoride as a dissolution catalyst in boiling nitric acid for an effective dissolution of the spent fuel. High corrosion rates were obtained for the candidate dissolver materials zircaloy-4 (Zr-4) and commercial pure titanium (CP-Ti grade 2) in boiling 11.5 M HNO{sub 3} + 0.05 M NaF. Complexing the fluoride ions either with Al(NO{sub 3}){sub 3} or ZrO(NO{sub 3}){sub 2} aided in decreasing the corrosion rates of Zr-4 and CP-Ti. From the obtained corrosion rates it is concluded that CP-Ti is a better dissolver material than Zr-4 for extended service life in boiling 11.5 M HNO{sub 3} + 0.05 M NaF, when complexed with 0.15 M ZrO(NO{sub 3}){sub 2}. XPS analysis confirmed the presence of TiO{sub 2} and absence of fluoride on the surface of CP-Ti samples, indicating that effective complexation had occurred in solution leading to passivation of the metal and imparting high corrosion resistance. - Highlights: • Zr-4 and CP-Ti exhibited high corrosion rate in boiling fluorinated nitric acid. • Corrosion rate decreased in fluorinated nitric acid containing ZrO(NO{sub 3}){sub 2} and Al(NO{sub 3}){sub 3}. • High inhibiting efficiency is exhibited by 0.15 M ZrO(NO{sub 3}){sub 2} when compared to Al(NO{sub 3}){sub 3}. • Corrosion rates of CP-Ti were negligible in complexed fluorinated nitric acid. • XPS analysis on CP-Ti confirmed the presence of TiO{sub 2} and absence of fluoride.

  1. Visualization of Fluoride Ions In Vivo Using a Gadolinium(III)-Coumarin Complex-Based Fluorescence/MRI Dual-Modal Probe.

    Science.gov (United States)

    Wang, Yue; Song, Renfeng; Feng, Huan; Guo, Ke; Meng, Qingtao; Chi, Haijun; Zhang, Run; Zhang, Zhiqiang

    2016-12-16

    A new Gadolinium(III)-coumarin complex, DO3A-Gd-CA, was designed and prepared as a dual-modal probe for simultaneous fluorescence and relaxivity responses to fluoride ions (F(-)) in aqueous media and mice. DO3A-Gd-CA was designed by using Gd(III) center as an MRI signal output unit and fluoride binding site, and the 4-(diethylamino)-coumarin-3-carboxylic acid (CA) as a fluorescence reporter. Upon the addition of fluoride ions to the solution of DO3A-Gd-CA, the liberation of the coordinated CA ligand led to a 5.7-fold fluorescence enhancement and a 75% increase in the longitudinal relaxivity (r₁). The fluorescent detection limit for fluoride ions was determined to be 8 μM based on a 3σ/slope. The desirable features of the proposed DO3A-Gd-CA, such as high sensitivity and specificity, reliability at physiological pH and low cytotoxicity enable its application in visualization of fluoride ion in mice. The successful in vivo imaging indicates that DO3A-Gd-CA could be potentially used in biomedical diagnosis fields.

  2. Direct observation of Nd{sup 3+} and Tm{sup 3+} ion distributions in oxy-fluoride glass ceramics containing PbF{sub 2} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jihong [School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Hongshan, Wuhan, Hubei 430070 (China); State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Hongshan, Wuhan, Hubei 430070 (China); Center for Information Materials, Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang, Gyeongbuk 790-784 (Korea, Republic of); Zhao, Zhiyong [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Hongshan, Wuhan, Hubei 430070 (China); Liu, Chao, E-mail: hite@whut.edu.cn [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Hongshan, Wuhan, Hubei 430070 (China); Zhang, Gaoke, E-mail: gkzhang@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Hongshan, Wuhan, Hubei 430070 (China); Zhao, Xiujian [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Hongshan, Wuhan, Hubei 430070 (China); Heo, Jong [Center for Information Materials, Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang, Gyeongbuk 790-784 (Korea, Republic of); Jiang, Yang [China Building Material Institute of Solar-Energy Application, Zhenjiang, Jiangsu 212009 (China)

    2014-12-15

    Nd{sup 3+} and Tm{sup 3+}, doped oxy-fluoride glasses and glass ceramics were prepared by conventional melt-quenching and subsequent heat-treatment, respectively. β-PbF{sub 2} nanocrystals with diameter 50 –100 nm formed in the glass matrix after heat treatment. The Stark splitting in absorption peaks, enhanced photoluminescence and prolonged lifetimes that β-PbF{sub 2} nanocrystal formation increased the luminescence of rare earth ions. Both Nd{sup 3+} and Tm{sup 3+} ions were incorporated into nanocrystals that were enriched in lead and fluorine, and deficient in oxygen. - Highlights: • EELS analysis for rare-earth ion distribution in oxy-fluoride glass ceramics • No significant changes in lifetimes of Nd{sup 3+}, while obvious change for Tm{sup 3+} • Direct evidence of Nd{sup 3+} and Tm{sup 3+} aggregation into fluoride nanocrystals.

  3. Effect of fluoridated water on intelligence in 10-12-year-old school children

    Science.gov (United States)

    Aravind, A.; Dhanya, R. S.; Narayan, Ajay; Sam, George; Adarsh, V. J.; Kiran, M.

    2016-01-01

    Aim: The aim of the present study was to evaluate the relationship of drinking water fluoride levels with children's intelligence quotient (IQ). Materials and Methods: Water was collected from initially identified endemic fluoride regions according to the geological research of Government of India. Fluoride concentration of the water was assessed by utilizing fluoride ion selective electrode, Orion 9609BN, and categorized on the basis of fluoride concentration into low, medium, and high-fluoride regions, i.e., Virajpet (low fluoride level 3 ppm). Government school from all three villages were selected randomly and IQ levels were assessed by using Raven's Standard Progressive Matrices. This test was conducted on each child in the study sample. Results: A significant inverse relationship was found between the fluoride concentration in drinking water and IQ (r value = −0.204; P < 0.000). It was observed that IQ level was negatively correlated with fluoride concentration in drinking water. Conclusion: It is concluded that IQ level was negatively correlated with fluoride level in drinking water. Factors that might affect children's IQ need to be considered, and it is necessary to devise solutions for preventing the harmful effects of excessive intake of fluoride ion to the body. PMID:28217543

  4. A receptor incorporating OH, NH and CH binding motifs for a fluoride selective chemosensor.

    Science.gov (United States)

    Xu, Liang; Li, Yongjun; Yu, Yanwen; Liu, Taifeng; Cheng, Songhua; Liu, Huibiao; Li, Yuliang

    2012-06-14

    An anion receptor combined different types of hydrogen bond donors such as OH, NH and CH groups has been synthesized. By rotation of the sub methyl group, this receptor showed evident (1)H NMR response to both fluoride and sulfate, while colorimetric and fluorescent responses were only observed in the presence of fluoride.

  5. Association between Urine Fluoride and Dental Fluorosis as a Toxicity Factor in a Rural Community in the State of San Luis Potosi

    OpenAIRE

    Lizet Jarquín-Yañez; José de Jesús Mejía-Saavedra; Nelly Molina-Frechero; Enrique Gaona; Diana Olivia Rocha-Amador; Olga Dania López-Guzmán; Ronell Bologna-Molina

    2015-01-01

    Objective. The aim of this study is to investigate urine fluoride concentration as a toxicity factor in a rural community in the state of San Luis Potosi, Mexico. Materials and Methods. A sample of 111 children exposed to high concentrations of fluoride in drinking water (4.13 mg/L) was evaluated. Fluoride exposure was determined by measuring urine fluoride concentration using the potentiometric method with an ion selective electrode. The diagnosis of dental fluorosis was performed by clinica...

  6. Fluoride distibution and the effect of some ions along Alexandria coastal Mediterranean seawater of Egypt

    Institute of Scientific and Technical Information of China (English)

    W. M. El-Sarraf; M. S. Masoud; A. A. Harfoush; GH. F. El-Said

    2003-01-01

    The coastal seawater of Mediterranean of Alexandria receives large amount of discharged waters containing industrial wastes, sewage, and agricultural and domestic drainage. Fluoride and some parameters were(chemical and physical) determined. The data gave indication that the content and the amount of the discharged water largely affect the chemical composition of the coastal water. Stepwise regression analysis was highly significant and the model was very fruitful, where the observed and calculated values were mostly concordant. This may indicated that there was a relation between fluoride content in coastal seawater and its content in the discharged water.

  7. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after...... (6 on fluoride mouth rinse, 10 on fluoride gel and 3 on fluoride foam); 6 had a low risk of bias while 2 had a moderate risk. All fluoride measures appeared to be beneficial in preventing crown caries and reversing root caries, but the quality of evidence was graded as low for fluoride mouth rinse......, moderate for fluoride gel and very low for acidulated fluoride foam. No conclusions could be drawn on the cost-effectiveness. CONCLUSIONS: This review, covering the recent decade, has further substantiated the evidence for a caries-preventive effect of fluoride mouth rinse, fluoride gel and foam...

  8. Enhanced solar photons harvesting of a-SiC:H solar cells with ZBLA fluoride glasses containing rare earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Song, Pei, E-mail: psong@sues.edu.cn; Zhang, Chaomin; Zhu, Pengfei

    2016-09-05

    As encapsulation glasses for a-SiC:H cells, Yb{sup 3+}/Ce{sup 3+}-Er{sup 3+} tri-doped ZBLA fluoride glasses were prepared using the high temperature melt-quenching method and the optical characteristic of the glass were measured. Depending on the nature of rare earth doped ZBLA fluoride glasses, both near infrared (low-energy) and ultraviolet (high-energy) solar photons can be transformed into visible photons. By downshifting the ultraviolet (280–350 nm) light combined with upconverting the near infrared (900–1100 nm) light, the glass can emit strong visible (500–700 nm) light, which matches well with the spectral responsivity of a-SiC:H cells. The conversion of non-absorption photons energies by upconversion and downshifting leads to promote the improvement of a-SiC:H cells performances, and measurement shows relatively increase of 7.6%–0.8% in cell efficiencies. - Highlights: • Yb{sup 3+}-Ce{sup 3+}-Er{sup 3+} tri-doped ZBLA fluoride glasses have been prepared. • An efficient energy transfer can occur from Yb{sup 3+} and Ce{sup 3+} ions to Er{sup 3+} ions. • Both ultraviolet and near-infrared photons can be converted into visible photons. • A-SiC:H cell efficiency is effectively raised by encapsulated with RE-ZBLA glass. • The emission of glasses matched well with the spectral response of a-SiC:H cell.

  9. One-Step Synthesis of Titanium Oxyhydroxy-Fluoride Rods and Research on the Electrochemical Performance for Lithium-ion Batteries and Sodium-ion Batteries.

    Science.gov (United States)

    Li, Biao; Gao, Zhan; Wang, Dake; Hao, Qiaoyan; Wang, Yan; Wang, Yongkun; Tang, Kaibin

    2015-12-01

    Titanium oxyhydroxy-fluoride, TiO0.9(OH)0.9F1.2 · 0.59H2O rods with a hexagonal tungsten bronze (HTB) structure, was synthesized via a facile one-step solvothermal method. The structure, morphology, and component of the products were characterized by X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), ion chromatograph, energy-dispersive X-ray (EDX) analyses, and so on. Different rod morphologies which ranged from nanoscale to submicron scale were simply obtained by adjusting reaction conditions. With one-dimension channels for Li/Na intercalation/de-intercalation, the electrochemical performance of titanium oxyhydroxy-fluoride for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) was also studied. Electrochemical tests revealed that, for LIBs, titanium oxyhydroxy-fluoride exhibited a stabilized reversible capacity of 200 mAh g(-1) at 25 mA g(-1) up to 120 cycles in the electrode potential range of 3.0-1.2 V and 140 mAh g(-1) at 250 mA g(-1) up to 500 cycles, especially; for SIBs, a high capacity of 100 mAh g(-1) was maintained at 25 mA g(-1) after 115 cycles in the potential range of 2.9-0.5 V.

  10. Dental fluorosis and urinary fluoride in 10-12 years old adolescents of Bushehr port

    Directory of Open Access Journals (Sweden)

    Giti Javan

    2006-02-01

    Full Text Available Background: Fluoride increases tooth resistance to dental caries, but mild toxicity due to excessive ingestion of fluoride can cause dental fluorosis. Drinking water naturally contains fluoride and is a major source of fluoride. In Bushehr port, drinking water is supplied from limestone springs with normal fluoride levels but dental fluorosis is observed. Methods: A total of 95 native school children (between the ages of 10-12 years old were randomly selected from four Bushehr port regions. Dental fluorosis, height and weight were examined. Probable attributing factors of dental fluorosis were also questioned. A 16 to 18 hours urinary fluoride concentration was measured with a fluoride ion selective electrode. Results: Dental fluorosis in four upper incisors was apparent in 52.6 % of the subjects. The urinary fluoride concentration was 2.18 mg/lit. Fluoride concentration in drinking water of schools ranged from 0.41 to 0.58 mg/lit. Forty percent of subjects were caries free. Conclusion: In spite of the normal range of fluoride concentration in the drinking water of Bushehr, dental fluorosis and urinary fluoride concentration are higher than the recommended ranges. Therefore, it is necessary to further investigate the amount and effects of fluoride ingestion in residents of Bushehr province.

  11. To immobilize polyethylene glycol-borate ester/lithium fluoride in graphene oxide/poly(vinyl alcohol for synthesizing new polymer electrolyte membrane of lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    Y. F. Huang

    2017-01-01

    Full Text Available Polymer electrolyte membranes (PEMs are potentially applicable in lithium-ion batteries with high safety, low cost and good performance. Here, to take advantages of ionic conductivity and selectivity of borate ester-functionalized small molecules as well as structural properties of polymer nanocomposite, a strategy of immobilizing as-synthesized polyethylene glycol-borate ester/lithium fluoride (B-PEG/LiF in graphene oxide/poly(vinyl alcohol (GO/PVA to prepare a PEM is put forward. Chemical structure of the PEM is firstly characterized by 1H-, 11B- and 19F-nuclear magnetic resonance spectra, and Fourier transform infrared spectroscopy spectra, respectively, and then is further investigated under consideration of the interactions among PVA, B-PEG and LiF components. The immobilization of B-PEG/LiF in PVA-based structure is confirmed. As the interactions within electrolyte components can be further tuned by GO, ionic conductivity (~10–3 S·cm–1, lithium-ion transfer number (~0.49, and thermal (~273 °C/electrochemical (>4 V stabilities of the PEM can be obtained, and the feasibility of PEMs applied in a lithium-ion battery is also confirmed. It is believed that such PEM is a promising candidate as a new battery separator.

  12. The effect of core and lanthanide ion dopants in sodium fluoride-based nanocrystals on phagocytic activity of human blood leukocytes

    Science.gov (United States)

    Sojka, Bartlomiej; Liskova, Aurelia; Kuricova, Miroslava; Banski, Mateusz; Misiewicz, Jan; Dusinska, Maria; Horvathova, Mira; Ilavska, Silvia; Szabova, Michaela; Rollerova, Eva; Podhorodecki, Artur; Tulinska, Jana

    2017-02-01

    Sodium fluoride-based β-NaLnF4 nanoparticles (NPs) doped with lanthanide ions are promising materials for application as luminescent markers in bio-imaging. In this work, the effect of NPs doped with yttrium (Y), gadolinium (Gd), europium (Eu), thulium (Tm), ytterbium (Yb) and terbium (Tb) ions on phagocytic activity of monocytes and granulocytes and the respiratory burst was examined. The surface functionalization of <10-nm NPs was performed according to our variation of patent pending ligand exchange method that resulted in meso-2,3-dimercaptosuccinic acid (DMSA) molecules on their surface. Y-core-based NCs were doped with Eu ions, which enabled them to be excited with UV light wavelengths. Cultures of human peripheral blood ( n = 8) were in vitro treated with five different concentrations of eight NPs for 24 h. In summary, neither type of nanoparticles is found toxic with respect to conducted test; however, some cause toxic effects (they have statistically significant deviations compared to reference) in some selected doses tested. Both core types of NPs (Y-core and Gd-core) impaired the phagocytic activity of monocytes the strongest, having minimal or none whatsoever influence on granulocytes and respiratory burst of phagocytic cells. The lowest toxicity was observed in Gd-core, Yb, Tm dopants and near-infrared nanoparticles. Clear dose-dependent effect of NPs on phagocytic activity of leukocytes and respiratory burst of cells was observed for limited number of samples.

  13. Intraoral fluoride levels after use of conventional and high-fluoride dentifrices.

    Science.gov (United States)

    Pessan, Juliano P; Conceição, Juliana M; Grizzo, Larissa T; Székely, Melinda; Fazakas, Zita; Buzalaf, Marília Ar

    2015-05-01

    This study aimed to evaluate saliva and plaque as indicators of intraoral fluoride (F) levels after the use of conventional and high-fluoride dentifrices. Subjects were randomly assigned to brush their teeth with conventional (1000 ppm F), high-fluoride (5000 ppm F), and placebo dentifrices (fluoride free) for 10 days, following a double-blind, crossover protocol. Saliva and plaque samples were collected on the morning of the 5(th) and 10th days, respectively at 1 and 12 h after brushing, and analyzed with an ion-selective electrode after HMDS-facilitated diffusion. Data were analyzed by two-way repeated measures ANOVA, Tukey's test and Spearman's correlation coefficient (p dentifrices when compared to values obtained for placebo, except plaque 12 h after the use of conventional dentifrice. A positive and significant correlation was found between fluoride concentrations in plaque and saliva for both times of sample collection. Both indicators assessed were able to detect significant differences among treatments and between times after brushing. The use of a high-fluoride dentifrice is able to significantly increase intraoral fluoride levels throughout the day, being therefore a useful therapy for patients at high caries risk. A dentifrice with high fluoride concentration could be regarded as a useful therapy of F delivery for high caries-risk patients, since intraoral F levels were sustained throughout most of the day after using this formulation.

  14. Fluoride release and recharge abilities of contemporary fluoride-containing restorative materials and dental adhesives.

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Koliniotou-Koumpia, Eugenia; Helvatzoglou-Antoniades, Maria; Kotsanos, Nikolaos

    2013-01-01

    The aim of this study was to evaluate the fluoride release of five fluoride-releasing restorative materials and three dental adhesives, before and after NaF solution treatment. Five restorative materials (Fuji IX GP, GC Corp.; Ketac N100, 3M ESPE; Dyract Extra, Dentsply; Beautifil II, Shofu Inc.; Wave, SDI) and three dental adhesives (Stae, SDI; Fluorobond II - Shofu Inc.; Prime & Bond NT, Dentsply) were investigated before and after NaF solution treatment. A fluoride ion-selective electrode was to measure fluoride concentrations. During the 86-day period before NaF solution treatment, Fuji IX GP released the highest amount of fluoride among the restorative materials while Prime & Bond NT was the highest among the dental adhesives. After NaF solution treatment, Fuji IX GP again ranked the highest in fluoride release among the restorative materials while Fluorobond II ranked the highest among dental adhesives. It was concluded that the compositions and setting mechanisms of fluoride-containing dental materials influenced their fluoride release and recharge abilities.

  15. Two dimensional fluoride ion conductor RbSn {2}F {5} studied by impedance spectroscopy and {19}F, {119}Sn, and {87}Rb NMR

    Science.gov (United States)

    Yamada, K.; Ahmad, M. M.; Ogiso, Y.; Okuda, T.; Chikami, J.; Miehe, G.; Ehrenberg, H.; Fuess, H.

    2004-07-01

    RbSn2F5 is a two-dimensional fluoride ion conductor. It undergoes a first-order phase transition to a superionic state at 368 K. The structure of the low temperature phase has been determined from the Rietveld analysis of the X-ray powder diffraction. The dynamic properties of the fluoride ions in RbSn2F5 have been studied by impedance spectroscopy and solid state NMR. The dc ionic conductivity of this sample shows an abrupt increase at the phase transition temperature. We have obtained the hopping frequency and the concentration of the charge carriers (F- ions) at different temperatures from the analysis of the conductivity spectra using Almond-West formalism. The estimated values of the charge carriers’ concentration agree well with that determined from the structure and were found to be independent of temperature. The relatively small value of the power-law exponent, n ≈ 0.55, supports the two-dimensional property of the investigated material. Furthermore, 19F NMR with simulation has suggested the diffusive motions of the fluoride ions between different sites. In contrast, 119Sn and 87Rb NMR spectra below 250 K supported the intrinsic disordered nature due to the random distribution of the fluoride ion vacancies.

  16. ANALYSIS OF SELECTED FLUORIDE WATER SAMPLES OF DIFFERENT AREAS OF JAIPUR, RAJASTHAN

    Directory of Open Access Journals (Sweden)

    Priyanka Dhingra

    2015-03-01

    Full Text Available This study was carried out to assess the fluoride concentration in groundwater in some rural areas of Jaipur city (Rajasthan, India, where groundwater is the main source of drinking water. Due to increased population, urbanization, industrialization, use of fertilizers water is highly polluted with different harmful contaminants. In present analysis a review of fluoride toxicity in drinking water along with the various deflouridation processes has been analyzed. Drinking water quality of 11 different places of Jaipur District was analyzed to identify the fluoride content in water. The drinking water samples were collected in clean polythene one liter cans and subjected for analysis in laboratory.

  17. Ion selective electrodes in environmental analysis

    Directory of Open Access Journals (Sweden)

    Radu Aleksandar

    2013-01-01

    Full Text Available An overview is given dealing with application of ion-selective electrodes (ISEs in environmental analysis. ISEs are placed into the context of the trend of development of sensors for extensive and frequent monitoring. Discussed are the issues such as sensing platforms and their mass-production, improvement of precision, diagnostic of sensor’s functionality, and development of reference electrodes and several examples of real-life application of ISEs in environmental analysis are given. The main emphasis of this article is directed towards summarizing recent of authors’ results during the past several years.

  18. A multi writable thiophene-based selective and reversible chromogenic fluoride probe with dual -NH functionality

    Science.gov (United States)

    Vishwakarma, Siddharth; Kumar, Ajit; Pandey, Abha; Upadhyay, K. K.

    2017-01-01

    A chromogenic fluoride probe bearing bis imine groups having dual -NH functionality (BSB) has been designed, synthesised and structurally characterized by its single crystal X-ray diffraction studies. The BSB could visually and spectroscopically recognise F- with high selectivity over other anions by exhibiting intense chromogenic response (from colourless to red) for F- in acetonitrile solution. The UV-visible titration and 1H NMR titration experiments indicated that the observed changes occur via a combined process including hydrogen bonding and deprotonation between the BSB and F-. Moreover theoretical calculations at the Density Functional Theory (DFT) level shed further light upon probe design strategy and the nature of interactions between BSB and F-. The limit of detection and binding constant of BSB towards F- were found to be 6.9 × 10- 7 M and 1.42 ± 0.069 × 108 M- 2 respectively. Finally, by using F- and H+ as chemical inputs and the absorbance as output, a INHIBIT logic gate was constructed, which exhibits "Multi-write" ability without obvious degradation in its optical output.

  19. Black Tea Source, Production, and Consumption: Assessment of Health Risks of Fluoride Intake in New Zealand

    Directory of Open Access Journals (Sweden)

    Declan T. Waugh

    2017-01-01

    Full Text Available In countries with fluoridation of public water, it is imperative to determine other dietary sources of fluoride intake to reduce the public health risk of chronic exposure. New Zealand has one of the highest per capita consumption rates of black tea internationally and is one of the few countries to artificially fluoridate public water; yet no information is available to consumers on the fluoride levels in tea products. In this study, we determined the contribution of black tea as a source of dietary fluoride intake by measuring the fluoride content in 18 brands of commercially available products in New Zealand. Fluoride concentrations were measured by potentiometric method with a fluoride ion-selective electrode and the contribution of black tea to Adequate Intake (AI and Tolerable Upper Intake Level (UL was calculated for a range of consumption scenarios. We examined factors that influence the fluoride content in manufactured tea and tea infusions, as well as temporal changes in fluoride exposure from black tea. We review the international evidence regarding chronic fluoride intake and its association with chronic pain, arthritic disease, and musculoskeletal disorders and provide insights into possible association between fluoride intake and the high prevalence of these disorders in New Zealand.

  20. Perspectives on Li and transition metal fluoride phosphates as cathode materials for a new generation of Li-ion batteries

    Directory of Open Access Journals (Sweden)

    Evgeny V. Antipov

    2015-01-01

    Full Text Available To satisfy the needs of rapidly growing applications, Li-ion batteries require further significant improvements of their key properties: specific energy and power, cyclability, safety and costs. The first generation of cathode materials for Li-ion batteries based on mixed oxides with either spinel or rock-salt derivatives has already been widely commercialized, but the potential to improve the performance of these materials further is almost exhausted. Li and transition metal inorganic compounds containing different polyanions are now considered as the most promising cathode materials for the next generation of Li-ion batteries. Further advances in cathode materials are considered to lie in combining different anions [such as (XO4n− and F−] in the anion sublattice, which is expected to enhance the specific energy and power of these materials. This review focuses on recent advances related to the new class of cathode materials for Li-ion batteries containing phosphate and fluoride anions. Special attention is given to their crystal structures and the relationships between structure and properties, which are important for their possible practical applications.

  1. Perspectives on Li and transition metal fluoride phosphates as cathode materials for a new generation of Li-ion batteries.

    Science.gov (United States)

    Antipov, Evgeny V; Khasanova, Nellie R; Fedotov, Stanislav S

    2015-01-01

    To satisfy the needs of rapidly growing applications, Li-ion batteries require further significant improvements of their key properties: specific energy and power, cyclability, safety and costs. The first generation of cathode materials for Li-ion batteries based on mixed oxides with either spinel or rock-salt derivatives has already been widely commercialized, but the potential to improve the performance of these materials further is almost exhausted. Li and transition metal inorganic compounds containing different polyanions are now considered as the most promising cathode materials for the next generation of Li-ion batteries. Further advances in cathode materials are considered to lie in combining different anions [such as (XO4) (n-) and F(-)] in the anion sublattice, which is expected to enhance the specific energy and power of these materials. This review focuses on recent advances related to the new class of cathode materials for Li-ion batteries containing phosphate and fluoride anions. Special attention is given to their crystal structures and the relationships between structure and properties, which are important for their possible practical applications.

  2. Creation of trapped electrons and holes in alkaline-earth fluoride crystals doped by rare-earth ions

    Science.gov (United States)

    Radzhabov, E.

    2002-06-01

    Defects in Ce 3+- and Eu 2+-doped alkaline-earth fluorides, created by vacuum ultraviolet (VUV) photons with energy lower than that of the band gap, were investigated by various methods: thermostimulated luminescence, photostimulated luminescence and optical absorption. The CaF 2:Eu 2+ thermoluminescence curves in the range of 60-330 K due to various types of trapped holes were the same after VUV illumination as after X-ray irradiation. Thermoluminescence curves of Ce 3+-doped alkaline-earth fluorides created by VUV illumination or X-ray irradiation were generally similar. However, Vk thermoluminescence peaks were absent in VUV-illuminated CaF 2:Ce 3+ and SrF 2:Ce 3+ crystals. Creation of Ce 2+ characteristic bands was observed in photostimulated luminescence spectra as well as in optical absorption spectra of vacuum ultraviolet-illuminated or X-ray-irradiated Ce 3+-doped crystals. The proposed mechanism of creation of trapped hole and trapped electron defects by vacuum ultraviolet illumination involves charge transfer-type transitions, in which the electron transfers from valence band to an impurity level, lying in the band gap. Comparison of all involved energies of transitions in the crystals investigated shows that the sum of all transition energies is less than that of the band gap by 1-3 eV. This energy difference can be considered as the energy of lattice relaxation around created Ce 2+ or Eu + ions.

  3. EELS spectroscopy of iron fluorides and FeFx/C nanocomposite electrodes used in Li-ion batteries.

    Science.gov (United States)

    Cosandey, Frederic; Al-Sharab, Jafar F; Badway, Fadwa; Amatucci, Glenn G; Stadelmann, Pierre

    2007-04-01

    A new type of positive electrode for Li-ion batteries has been developed recently based on FeF3/C and FeF2/C nanocomposites. The microstructural and redox evolution during discharge and recharge processes was followed by electron energy loss spectroscopy (EELS) to determine the valence state of Fe by measuring the Fe L3 line energy shift and from Fe L3/L2 line intensity ratios. In addition, transition metal fluorides were found to be electron beam sensitive, and the effect of beam exposure on EELS spectra was also investigated. The EELS results indicate that for both FeF3/C and FeF2/C nanocomposite systems, a complete reduction of iron to FeO is observed upon discharge to 1.5 V with the formation of a finer FeO/LiF subnanocomposite ( approximately 7 nm). Upon complete recharging to 4.5 V, EELS data reveal a reoxidation process to a Fe2+ state with the formation of a carbon metal fluoride nanocomposite related to the FeF2 structure.

  4. An easy prepared dual-channel chemosensor for selective and instant detection of fluoride based on double Schiff-base

    Science.gov (United States)

    Leng, Yan-Li; Zhang, Jian-Hui; Li, Qiao; Zhang, You-Ming; Lin, Qi; Yao, Hong; Wei, Tai-Bao

    2016-10-01

    A colorimetric and fluorescent dual-channel fluoride chemosensor N,N‧-bis (4-diethylaminosalicylidene) hydrazine (sensor S) bearing two imine groups has been designed and synthesized. This structurally simple probe displays rapid response and high selectivity for fluoride over other common anions (Cl-, Br-, I-, AcO-, H2PO4-, HSO4-, ClO4-, CN- and SCN-) in a highly polar aqueous DMSO solution. Mechanism studies suggested that the sensor firstly combined with F- through hydrogen bonds and then experienced the deprotonation process at higher concentrations of F- anion to the two Ar-OH groups. The detection limit was 5.78 × 10- 7 M of F-, which points to the high detection sensitivity. Test strips based on sensor S were fabricated, which could act as a convenient and efficient F- test kit to detect F- for "in-the-field" measurement.

  5. Studies of the optical spectra and spin-Hamiltonian parameters for the trivalent ytterbium ions in lithium yttrium fluoride crystals

    Science.gov (United States)

    Feng, W. L.; Han, Z.; Zhong, Y. C.

    In this paper, the crystal field (CF) levels and spin-Hamiltonian (SH) parameters (g factors g∥ and g⊥ and hyperfine structure constants A∥ and A⊥) of the rare-earth ion Yb3+ in lithium yttrium fluoride crystals are calculated under D2d point symmetry assumption. Two main methods are used in the calculation to study the SH parameters: one is the perturbation theory method and the other is the complete diagonalization (energy matrix) method (CDM). Comparing the calculated results with the experimental data, we can see that the CDM is more effective to calculate the SH parameters. In addition, the CF J-mixing of all excited-state multiplets into the ground-state multiplet 2F7/2 is considered. The validity of the calculated results is discussed.

  6. A new adsorbent of a Ce ion-implanted metal-organic framework (MIL-96) with high-efficiency Ce utilization for removing fluoride from water.

    Science.gov (United States)

    Yang, Xuan; Deng, Shuangshuang; Peng, Fumin; Luo, Tao

    2017-02-14

    A novel Ce(iii) ion-implanted aluminum-trimesic metal-organic framework (Ce-MIL-96) was synthesized for the first time via alcohol-solvent incipient wetness impregnation. Compared to previously reported Ce-contained adsorbents, the fluoride adsorption performance of the new ion-implanted metal-organic framework demonstrated much higher adsorption capacity and more efficient regeneration of Ce. In a wide pH range of 3 to 10, Ce-MIL-96 maintained constant adsorption performance for fluoride, and the residual Ce and Al in the treated solution were below the safe limits in drinking water. The maximum adsorption capacity of Ce-MIL-96 was 38.65 mg g(-1) at 298 K. Excluding the contribution of MIL-96, the maximum adsorption capacity of Ce ions was 269.75 mg g(-1), which demonstrated that the service efficiency of cerium in Ce-MIL-96 is about 6 times that in Ce2O3, nearly 10 times that in Ce-mZrp, and double that in Mn-Ce oxides. There was no significant influence on fluoride removal by Ce-MIL-96 due to the presence of chloride, nitrate, sulfate, bicarbonate or phosphate. Moreover, the adsorption capacity of Ce-MIL-96 remained at more than 70% after nine cycles of adsorption-desorption. Due to this excellent adsorption performance and its regeneration properties, Ce-MIL-96 is a promising adsorbent for the removal of fluoride from groundwater.

  7. Influence of fluoride ions on stability of the oxide form of radon in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Avrorin, V.V.; Krasikova, R.N.; Nefedov, V.D.; Toropova, M.A.

    1988-01-01

    It has already been shown that during the fluorination of radon a higher radon fluoride is formed, whose hydrolysis leads to the formation of radon oxide, whereby the latter is probably present in the anionic form RnO/sub 3/F/sup -/. This supposition is confirmed by the ability of the form of radon studied to be isomorphously coprecipitated with CsXeO/sub 3/F x nH/sub 2/O. This work is devoted to the study of the kinetics of decomposition of the oxide form of radon in an aqueous solution.

  8. Scintillating 99Tc Selective Ion Exchange Resins

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell Greenhalgh; Richard D. Tillotson

    2012-07-01

    Scintillating technetium (99Tc) selective ion exchange resins have been developed and evaluated for equilibrium capacities and detection efficiencies. These resins can be utilized for the in-situ concentration and detection of low levels of pertechnetate anions (99TcO4-) in natural waters. Three different polystyrene type resin support materials were impregnated with varying amounts of tricaprylmethylammonium chloride (Aliquat 336) extractant, several different scintillating fluors and wavelength shifters. The prepared resins were contacted batch-wise to equilibrium over a wide range of 99TcO4- concentrations in natural water. The measured capacities were used to develop Langmuir adsorption isotherms for each resin. 99Tc detection efficiencies were determined and up to 71.4 ± 2.6% was achieved with some resins. The results demonstrate that a low level detection limit for 99TcO4- in natural waters can be realized.

  9. Changes in the Concentration of Ions in Saliva and Dental Plaque after Application of CPP-ACP with and without Fluoride among 6-9 Year Old Children

    Directory of Open Access Journals (Sweden)

    Poureslami H

    2017-03-01

    Full Text Available Statement of Problem: The casein phospho peptide-amorphous calcium phosphate with or without fluoride (CPP-ACPF and CPP-ACP respectively are of considerably new materials which are highly recommended for prevention of dental caries. However, there is a shortage in literature on how they affect the ion concentration of saliva or dental plaque. Objectives: The aim of this study was to evaluate the concentration of calcium, phosphate and fluoride in the plaque and saliva of children with Early Childhood Caries (ECC after applying the CPP-ACP paste in comparison with the use of CPP- ACPF paste. Materials and Methods: One ml of un-stimulated saliva of 25 preschool children was collected and then 1 mg of the plaque sample was collected from the buccal surfaces of the two first primary molars on the upper jaw. CPP-ACP as well as CPP- ACPF pastes were applied on the tooth surfaces in two separate steps. In steps, plaque and saliva sampling was performed after 60 minutes. The amount of calcium ions was measured by Atomic Absorption Device and the amount of phosphate and fluoride ions was measured by Ion Chromatography instrument. Data were analyzed using Repeated Measurements ANOVA at a p < 0.05 level of significance. Results: Application of both CPP-ACPF and CPP-ACP significantly increased the concentration of calcium, phosphate, and fluoride in both saliva and dental plaque. Moreover, significantly higher salivary fluoride concentration was seen after application of CPP-ACPF compared to CPP-ACP. No other significant difference was observed between these two materials. Conclusions: CPP-ACPF can be more useful than CPP-ACP in protecting the primary teeth against caries process, especially when there is poor hygiene.

  10. Method for the analysis of total fluoride in fluoride-releasing dental varnishes.

    Science.gov (United States)

    Carey, C M; Coleman, S S

    2014-01-01

    Today's fluoride-releasing varnishes (F-varnish) contain a wide variety of ingredients which present analytical challenges for measuring their total fluoride content. This study reports improved methods to measure fluoride content in F-varnishes. Six different commercially available F-varnishes that contain difluorosilane (0.1% F) or NaF (2.26% F) alone or in combination with calcium-phosphates were analyzed. In a vial, 1-3 drops (0.05-0.15 g) of varnish product was dispensed, dissolved in chloroform, equilibrated in TISAB and analyzed via fluoride ion-selective electrode. The average weight percentage of fluoride for all F-varnishes containing NaF ranged from 2.03 to 2.24% F, which is within 90% of the declared label concentration of 2.26% F. Analysis of the difluorosilane-containing product required an additional hydrolysis step. ANOVA found no significant difference between the 5% NaF varnishes at p fluoride analysis yields reliable and reproducible results and can be used for a wide variety of F-varnishes. The standard uncertainty for this method is ±4%. This method may become the basis for national and international standards that ensure the F-varnish products used in clinical practice have the fluoride content declared in the product literature. © 2014 S. Karger AG, Basel.

  11. Method for the Analysis of Total Fluoride in Fluoride-Releasing Dental Varnishes

    Science.gov (United States)

    Carey, C.M.; Coleman, S.S.

    2016-01-01

    Today’s fluoride-releasing varnishes (F-varnish) contain a wide variety of ingredients which present analytical challenges for measuring their total fluoride content. This study reports improved methods to measure fluoride content in F-varnishes. Six different commercially available F-varnishes that contain difluorosilane (0.1% F) or NaF (2.26% F) alone or in combination with calcium-phosphates were analyzed. In a vial, 1–3 drops (0.05–0.15 g) of varnish product was dispensed, dissolved in chloroform, equilibrated in TISAB and analyzed via fluoride ion-selective electrode. The average weight percentage of fluoride for all F-varnishes containing NaF ranged from 2.03 to 2.24% F, which is within 90% of the declared label concentration of 2.26% F. Analysis of the difluorosilane-containing product required an additional hydrolysis step. ANOVA found no significant difference between the 5% NaF varnishes at p fluoride analysis yields reliable and reproducible results and can be used for a wide variety of F-varnishes. The standard uncertainty for this method is ±4%. This method may become the basis for national and international standards that ensure the F-varnish products used in clinical practice have the fluoride content declared in the product literature. PMID:24557443

  12. Fluoride concentration in urine after silver diamine fluoride application on tooth enamel

    Science.gov (United States)

    Sari, D. L.; Bahar, A.; Gunawan, H. A.; Adiatman, M.; Rahardjo, A.; Maharani, D. A.; Toptanci, I. R.; Yavuz, I.

    2017-08-01

    Silver Diammine Fluoride (SDF), which contains fluoride, is known to inhibit tooth enamel demineralization and increase fluoride concentrations in saliva and urine. The aim of this study is to analyze the fluoride concentration in urine after application of SDF on tooth enamel. Urine from four subjects was collected prior to, 30 minutes after, and two and three hours after the application of SDF, and an ion-selective electrode was used to measure the fluoride concentrations. There was no significant difference between time 1 and time 2, time 1 and time 3, time 1 and time 4, time 2 and 3 (p > 0.05), and there was a significant difference between time 2 and time 4 as well as time 3 and time 4 (p < 0.05). There was a decrease in the concentration of fluoride ions in urine from the baseline to 30 minutes after application, and an increase from baseline to two and three hours after the application of SDF.

  13. Quantum Interference and Selectivity through Biological Ion Channels

    Science.gov (United States)

    Salari, Vahid; Naeij, Hamidreza; Shafiee, Afshin

    2017-01-01

    The mechanism of selectivity in ion channels is still an open question in biology for more than half a century. Here, we suggest that quantum interference can be a solution to explain the selectivity mechanism in ion channels since interference happens between similar ions through the same size of ion channels. In this paper, we simulate two neighboring ion channels on a cell membrane with the famous double-slit experiment in physics to investigate whether there is any possibility of matter-wave interference of ions via movement through ion channels. Our obtained decoherence timescales indicate that the quantum states of ions can only survive for short times, i.e. ≈100 picoseconds in each channel and ≈17–53 picoseconds outside the channels, giving the result that the quantum interference of ions seems unlikely due to environmental decoherence. However, we discuss our results and raise few points, which increase the possibility of interference. PMID:28134331

  14. Safety Evaluation of Fluoride Content in Tea Infusions Consumed in the Azores-a Volcanic Region with Water Springs naturally Enriched in Fluoride.

    Science.gov (United States)

    Linhares, Diana Paula Silva; Garcia, Patrícia Ventura; Amaral, Leslie; Ferreira, Teresa; Dos Santos Rodrigues, Armindo

    2017-01-24

    Tea is the second most commonly consumed beverage in the world. It is well recognized that the consumption of tea in high quantities can promote the development of fluorosis. The main objective of this study is to estimate the exposure to fluoride in the Azores through drinking tea prepared with water from different volcanic locations, by i) investigating the fluoride (F) content of various commercial brands of tea (Camellia sinensis) marketed in Azores and ii) comparing tea releasing rates of F according to brewing time, considering the fluoride concentration in the different types of water used for the infusion. Fluoride contents were determined by ion-selective electrode in 30 samples of drinking water from three different locations and in 450 samples of tea (black and green tea) from three different brands. Fluoride concentration in water ranged from 0.29 to 1.56 ppm (Porto Formoso and Sete Cidades village, respectively). Fluoride concentrations increased with brewing time, reaching the highest values in the Azorean black and green tea infusions. For all the studied brands, a negative correlation was found between tea fluoride contents and the pH of the water used to prepare the infusion. Fluoride concentration in infusions was significantly associated with the background fluoride concentration in drinking water. Since the fluoride concentration in groundwater varies accordingly to the geological conditions and tea consumption can contribute to fluoride intake, it is important to define the limits for tea consumption, particularly in fluoride-rich areas. Graphical Abstract Fluoride concentrations in black and green tea for 3 minutes of brewing time and, association between fluoride concentration and pH with brewing time.

  15. Effect of Fluoride Ions on the Anodic Behavior of Mill Annealed and Aged Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, M A; Carranza-, R M; Rebak, R B

    2003-10-07

    Alloy 22 (N06022) is the current candidate alloy to fabricate the external wall of the high level nuclear waste containers for the Yucca Mountain repository. It was of interest to study and compare the general and localized corrosion susceptibility of Alloy 22 in saturated NaF solutions ({approx} 1 M NaF) at 90 C. Standard electrochemical tests such as cyclic potentiodynamic polarization, amperometry, potentiometry, and electrochemical impedance spectroscopy were used. Studied variables included the solution pH and the alloy microstructure (thermal aging). Results show that Alloy 22 is highly resistant to general and localized corrosion in pure fluoride solutions. Thermal aging is not detrimental and even seems to be slightly beneficial for general corrosion in alkaline solutions.

  16. Characterization of Cu(Ⅱ) Ion Adsorption Behavior of the Polyacrylic Acid-Polyvinylidene Fluoride Blended Polymer

    Institute of Scientific and Technical Information of China (English)

    SONG Laizhou; WANG Jibin; ZHENG Oiuyan; ZHANG Zunju

    2008-01-01

    A blended polymer adsorbent prepared using acrylic acid and polyvinylidene fluoride was used to remove copper from aqueous solutions. The polymer was prepared using thermally induced polymerization and phase inversion. The blended polymer was characterized by X-ray diffraction analysis (XRD), environ- mental scanning electron microscopy (ESEM), X-ray photoelectron spectroscopy (XPS), and N2 adsorp- tion/desorption experiments. The sorption data was fit to linearized adsorption isotherms of the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms models. The batch sorption kinetics was evaluated using pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic reaction models. △H0 is greater than O, △G0 is lower than O, and △S0 is greater than O, which shows that the adsorption of Cu (Ⅱ) by the blended polymer is a spontaneous, endothermic process. The adsorption isotherm fits better to the Freundlich isotherm model and the pseudo-second-order kinetics model gives a better fit to the batch sorp- tion kinetics. The adsorption mechanism is assumed to be ion exchange between the cupric ion and the cerboxylic acid functional group of the blended polymer.

  17. Excited state dynamics of the Ho3+ ions in holmium singly doped and holmium, praseodymium-codoped fluoride glasses

    Science.gov (United States)

    Librantz, André Felipe Henriques; Jackson, Stuart D.; Jagosich, Fabio Henrique; Gomes, Laércio; Poirier, Gaël; Ribeiro, Sidney José Lima; Messaddeq, Younes

    2007-06-01

    The deactivation of the two lowest excited states of Ho3+ was investigated in Ho3+ singly doped and Ho3+, Pr3+-codoped fluoride (ZBLAN) glasses. We establish that 0.1-0.3mol% Pr3+ can efficiently deactivate the first excited (I75) state of Ho3+ while causing a small reduction of ˜40% of the initial population of the second excited (I65) state. The net effect introduced by the Pr3+ ion deactivation of the Ho3+ ion is the fast recovery of the ground state of Ho3+. The Burshstein model parameters relevant to the Ho3+→Pr3+ energy transfer processes were determined using a least squares fit to the measured luminescence decay. The energy transfer upconversion and cross relaxation parameters for 1948, 1151, and 532nm excitations of singly Ho3+-doped ZBLAN were determined. Using the energy transfer rate parameters we determine from the measured luminescence, a rate equation model for 650nm excitation of Ho3+-doped and Ho3+, Pr3+-doped ZBLAN glasses was developed. The rate equations were solved numerically and the population inversion between the I65 and the I75 excited states of Ho3+ was calculated to examine the beneficial effects on the gain associated with Pr3+ codoping.

  18. Simultaneous determination of fluoride, chloride, sulfate, phosphate,monofluorophosphate, glycerophosphate, sorbate, and saccharin in gargles by ion chromatography

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yan-zhen; ZHOU Yan-chun; LIU Li; ZHU Yan

    2007-01-01

    Simple, reliable and sensitive analytical methods to determine anticariogenic agents, preservatives, and artificial sweeteners contained in commercial gargles are necessary for evaluating their effectiveness, safety, and quality. An ion chromatography (IC) method has been described to analyze simultaneously eight anions including fluoride, chloride, sulfate, phosphate,monofluorophosphate, glycerophosphate (anticariogenic agents), sorbate (a preservative), and saccharin (an artificial sweetener)in gargles. In this IC system, we applied a mobile phased gradient elution with KOH, separation by IonPac AS18 columns, and suppressed conductivity detection. Optimized analytical conditions were further evaluated for accuracy. The relative standard deviations (RSDs) of the inter-day's retention time and peak area of all species were less than 0.938% and 8.731%, respectively,while RSDs of 5-day retention time and peak area were less than 1.265% and 8.934%, respectively. The correlation coefficients for targeted analytes ranged from 0.999 7 to 1.000 0. The spiked recoveries for the anions were 90%~102.5%. We concluded that the method can be applied for comprehensive evaluation of commercial gargles.

  19. Potentiometric response and mechanism of anionic recognition of heterocalixarene-based ion selective electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Shishkanova, T.V. [Department of Analytical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic)]. E-mail: tatiana.shishkanova@vscht.cz; Sykora, D. [Department of Analytical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Sessler, J.L. [Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712-0615 (United States); Kral, V. [Department of Analytical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2007-03-28

    The ion selective electrode (ISE)-based potentiometric approach is shown to be an effective means of characterizing the anion recognition sites in the molecular receptor calix[2]pyridino[2]pyrrole (CPP). In particular, potentiometric pH-measurements involving the use of experimental PVC-membranes based on CPP revealed the existence of both mono- and diprotonated forms of the receptor under readily accessible conditions. Based on these analyses, apparent surface protonation constants for this heterocalixarene were found to lie between 8.5-8.9 (pK {sub B1}) and 3.3-3.8 (pK {sub B2}). CPP was found to interact with targeted anionic analytes based on both coulombic and hydrogen bond interactions, as inferred from varying the kinds of ionic sites present within the membrane phase. Potentiometric selectivity studies revealed that CPP preferred 'Y-shaped' anions (e.g. acetate, lactate, benzoate) over spherical anions (e.g. fluoride and chloride), fluoride over chloride within the set of spherical anions, and the ortho-isomer over the corresponding meta- and para-isomers in the case of hydroxybenzoate (salicylate and congeners). In the context of this study, the advantages of potentiometric determinations of acetylsalicylic acid using optimized PVC-membranes based on CPP relative to more conventional PVC-membrane ISEs based on traditional anion exchanger were also demonstrated.

  20. Swift heavy ion irradiation effects in {alpha} poly(vinylidene fluoride); Etude des effets induits par les ions lourds energetiques dans le poly(fluorure de vinylidene)

    Energy Technology Data Exchange (ETDEWEB)

    Le Bouedec, A

    1999-11-29

    The goal of this study is to characteristic and to localised defects created in {alpha} Poly (vinylidene fluoride) after swift heavy ion irradiations. PVDF films are irradiated with several Swift Heavy Ions (SHI), in the electronic stopping power (dE/dx){sub e}, in order to study the influence of irradiation parameters (absorbed dose, ion). These irradiated films are studied by different analysis techniques such as FTIR, ESR (X and Q band) spectroscopies and DSC. The crystalline level of PVDF is about 50% and we follow it destruction and amorphization as the absorbed dose increase by DSC and FTIR studies. The variation of the various FTIR bands allow us to observe the unsaturations induced by SHI radiations. Two sets of defects are observed: those which yield is sensitive to an increase of (dE/dx){sub e} and those that are not. A spatial distribution of the various defects within the talent track is provided and defects that are difficult to create are the closest of the ion path. The different kind of radicals created after irradiations are studied by ESR spectroscopy. Alkyl, peroxy and polyenyl radicals are detected after SHI radiations like after electron or {gamma} irradiations. Their yield of creation is independent of (dE/dx){sub e} and their localised in the crystalline zone or/and at the interfacial zone between crystalline and amorphous one. An other kind of radicals is created only after SHI radiations that are specific of the SHI-polymer interaction. We observe that these radicals are localised on a carbon cluster, in the core of the latent track for low doses and highly sensitive at the (dE/dx){sub e} of the ion. (author)

  1. Risk Assessment of Fluoride Intake from Tea in the Republic of Ireland and its Implications for Public Health and Water Fluoridation.

    Science.gov (United States)

    Waugh, Declan T; Potter, William; Limeback, Hardy; Godfrey, Michael

    2016-02-26

    The Republic of Ireland (RoI) is the only European Country with a mandatory national legislation requiring artificial fluoridation of drinking water and has the highest per capita consumption of black tea in the world. Tea is a hyperaccumulator of fluoride and chronic fluoride intake is associated with multiple negative health outcomes. In this study, fifty four brands of the commercially available black tea bag products were purchased and the fluoride level in tea infusions tested by an ion-selective electrode method. The fluoride content in all brands tested ranged from 1.6 to 6.1 mg/L, with a mean value of 3.3 mg/L. According to our risk assessment it is evident that the general population in the RoI is at a high risk of chronic fluoride exposure and associated adverse health effects based on established reference values. We conclude that the culture of habitual tea drinking in the RoI indicates that the total cumulative dietary fluoride intake in the general population could readily exceed the levels known to cause chronic fluoride intoxication. Evidence suggests that excessive fluoride intake may be contributing to a wide range of adverse health effects. Therefore from a public health perspective, it would seem prudent and sensible that risk reduction measures be implemented to reduce the total body burden of fluoride in the population.

  2. Risk Assessment of Fluoride Intake from Tea in the Republic of Ireland and its Implications for Public Health and Water Fluoridation

    Science.gov (United States)

    Waugh, Declan T.; Potter, William; Limeback, Hardy; Godfrey, Michael

    2016-01-01

    The Republic of Ireland (RoI) is the only European Country with a mandatory national legislation requiring artificial fluoridation of drinking water and has the highest per capita consumption of black tea in the world. Tea is a hyperaccumulator of fluoride and chronic fluoride intake is associated with multiple negative health outcomes. In this study, fifty four brands of the commercially available black tea bag products were purchased and the fluoride level in tea infusions tested by an ion-selective electrode method. The fluoride content in all brands tested ranged from 1.6 to 6.1 mg/L, with a mean value of 3.3 mg/L. According to our risk assessment it is evident that the general population in the RoI is at a high risk of chronic fluoride exposure and associated adverse health effects based on established reference values. We conclude that the culture of habitual tea drinking in the RoI indicates that the total cumulative dietary fluoride intake in the general population could readily exceed the levels known to cause chronic fluoride intoxication. Evidence suggests that excessive fluoride intake may be contributing to a wide range of adverse health effects. Therefore from a public health perspective, it would seem prudent and sensible that risk reduction measures be implemented to reduce the total body burden of fluoride in the population. PMID:26927146

  3. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after an el...... brushing with fluoride toothpaste....

  4. Fluoride rechargability of a non-resin auto-cured glass ionomer cement from a fluoridated dentifrice: An in vitro study

    Directory of Open Access Journals (Sweden)

    A Rao

    2011-01-01

    Full Text Available Background: In addition to their fluoride-releasing properties, glass ionomer cement (GICs have the ability to reuptake and release fluorides from commonly used sources like fluoridated dentifrices. This property has the potential to provide a continuous low concentration of fluoride in the saliva aiding in caries prevention. The superior fluoride-recharging abilities of resin-modified GICs over conventional GICs have been documented. The manufacturer of a non-resin, auto-cured GIC (GC Fuji VII claims fluoride release from the product to be about six times that of conventional GIC. It was hypothesized that perhaps this high fluoride release could translate into a high reuptake and release, when exposed to a 1 000 ppm fluoridated dentifrice every day, thus providing increased fluoride levels in saliva. Aims: This study therefore examined fluoride-recharging abilities of the non-resin, auto-cured glass ionomer cement from a 1 000 ppm fluoridated dentifrice and compared it with resin-modified glass ionomer cement. Materials and Methods: Twelve glass ionomer discs each of resin-modified glass ionomer cement (GC Fuji II L C, Group 1 and the non-resin, auto-cured glass ionomer cement (GC Fuji VII, Group 2 were prepared with precise dimensions of 9 x 2 mm. The 12 specimens in each group were further subdivided into two subgroups of six each. Subgroup A involved no fluoride treatment (Control. Subgroup B involved application of a 1 000 ppm dentifrice for 2 minutes twice daily with a soft toothbrush. The disc-specimens were then suspended in airtight plastic bottles containing exactly 20 ml double distilled water. The fluoride concentration of the water in which the specimen discs were immersed was measured by means of a fluoride ion selective electrode connected to an ion selective electrode meter/digital ion analyzer at 1, 2, 7, 15, and 30 days. Statistical Analysis: It was performed using the Kruskal-Wallis Test. Results and Conclusion: Fuji VII

  5. Estimation of fluoride intake from milk-based infant formulas and baby foods.

    Science.gov (United States)

    Noh, Hie Jin; Sohn, Woosung; Kim, Baek Il; Kwon, Ho Keun; Choi, Choong Ho; Kim, Hae-Young

    2015-03-01

    The aim of this study was to examine the amount of fluoride ingested from infant formula and baby food in infants aged up to 6 months in South Korea. The fluoride content of 20 commercially available formulas and 8 baby food samples from 4 different brands was measured using a modified microdiffusion method and fluoride ion selective electrode. The amount of fluoride (F) ingested by infants was estimated assuming that the samples were reconstituted with water containing 0, 0.5, 0.8, and 1.0 ppm F. When the reconstituted formulas and baby foods contained 0.8 ppm F water, the infants were estimated to ingest fluoride in the range of 0.018 to 0.298 mg/kg/day. The findings of this study suggest that there is a need for clear guidelines for fluoride consumption by infants that should be followed by manufacturers and parents. © 2013 APJPH.

  6. Novel polyvinylidene fluoride nanofiltration membrane blended with functionalized halloysite nanotubes for dye and heavy metal ions removal

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Guangyong [State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); He, Yi, E-mail: heyi@swpu.edu.cn [State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Zhan, Yingqing; Zhang, Lei; Pan, Yang; Zhang, Chunli; Yu, Zongxue [State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500 (China)

    2016-11-05

    Highlights: • A novel PVDF nanofiltration membrane was prepared by incorporation of A-HNTs. • HNTs dispersed well in membrane matrix after APTES modification. • The membrane exhibited excellent hydrophilicity and antifouling properties. • A high dye and heavy metal ions removal was realized by membrane separation. - Abstract: Membrane separation is an effective method for the removal of hazardous materials from wastewater. Halloysite nanotubes (HNTs) were functionalized with 3-aminopropyltriethoxysilane (APTES), and novel polyvinylidene fluoride (PVDF) nanofiltration membranes were prepared by blending with various concentrations of APTES grafted HNTs (A-HNTs). The morphology structure of the membranes were characterized by scanning electron microscope (SEM) and atomic force microscopy (AFM). The contact angle (CA), pure water flux (PWF) and antifouling capacity of membranes were investigated in detail. In addition, the separation performance of membranes were reflected by the removal of dye and heavy metal ions in simulated wastewater. The results revealed that the hydrophilicity of A-HNTs blended PVDF membrane (A-HNTs@PVDF) was enhanced significantly. Owing to the electrostatic interaction between membrane surface and dye molecules, the dye rejection ratio of 3% A-HNTs@PVDF membrane reached 94.9%. The heavy metal ions rejection ratio and adsorption capacity of membrane were also improved with the addition of A-HNTs. More importantly, A-HNTs@PVDF membrane exhibited excellent rejection stability and reuse performances after several times fouling and washing tests. It can be expected that the present work will provide insight into a new method for membrane modification in the field of wastewater treatment.

  7. Urinary fluoride excretion after application of fluoride varnish and use of fluoride toothpaste in young children.

    Science.gov (United States)

    Lockner, Frida; Twetman, Svante; Stecksén-Blicks, Christina

    2017-01-20

    The efficacy and safety of combined use of topical fluoride products are essential issues that must be monitored. To assess urinary excretion of fluoride after application of two different dental varnishes containing 2.26% fluoride in 3- to 4-year-old children and to compare the levels with and without parallel use of fluoride toothpaste. Fifteen healthy children were enrolled to a randomized crossover trial that was performed in two parts: Part I with twice-daily tooth brushing with fluoride toothpaste and Part II with twice-daily brushing with a non-fluoride toothpaste. After a 1-week run-in period, 0.1 mL of the two fluoride varnishes (Duraphat and Profluorid Varnish) was topically applied in a randomized order. Baseline and experimental urine was collected during 6-h periods. The fluoride content was determined with an ion-sensitive electrode. There was a statistically significant increase in the 6-h fluoride excretion after application of both experimental varnishes, with and without parallel use of fluoride toothpaste (P fluoridated toothpaste was used, the mean fluoride excretion was 0.20 mg/6 h after application of Duraphat and 0.29 mg/6 h after application of Profluorid Varnish (P = 0.18). Topical applications of 0.1 mL of fluoride varnish significantly increased the 6-h fluoride excretion. As some individuals displayed excretion levels exceeding the optimal fluoride exposure, a restricted use of fluoride toothpaste in connection with the varnish applications would decrease fluoride exposure. © 2017 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. Variable selectivity of the Hitachi chemistry analyzer chloride ion-selective electrode toward interfering ions.

    Science.gov (United States)

    Wang, T; Diamandis, E P; Lane, A; Baines, A D

    1994-02-01

    Chloride measurements by ion-selective electrodes are vulnerable to interference by anions such as iodide, thiocyanate, nitrate, and bromide. We have found that the degree of interference of these anions on the Hitachi chemistry analyzer chloride electrode varies from electrode to electrode and this variation can even occur within the same lot of membrane. This variation is not dependent upon the length of time the cartridge has been in the analyzer because no correlation existed between the usage time and the electrode response to interfering ions. Neither is this variation due to the deterioration of the electrode because all electrodes tested had calibration slopes within the manufacturer's specification. Our study, however, showed that even after repeated exposure to a plasma sample containing 2 mM thiocyanate, the chloride electrode was still able to accurately measure the chloride in plasma without thiocyanate, thus confirming that a carryover effect does not exist from a previous thiocyanate-containing sample.

  9. Monitoring of fluoride in water samples using a smartphone

    Energy Technology Data Exchange (ETDEWEB)

    Levin, Saurabh [Akvo Foundation (Netherlands); Krishnan, Sunderrajan [INREM Foundation (India); Rajkumar, Samuel; Halery, Nischal; Balkunde, Pradeep [Akvo Foundation (Netherlands)

    2016-05-01

    In several parts of India, groundwater is the only reliable, year round source for drinking water. Prevention of fluorosis, a chronic disease resulting from excess intake of fluoride, requires the screening of all groundwater sources for fluoride in endemic areas. In this paper, the authors present a field deployable colorimetric analyzer based on an inexpensive smartphone embedded with digital camera for taking photograph of the colored solution as well as an easy-fit, and compact sample chamber (Akvo Caddisfly). Phones marketed by different smartphone makers were used. Commercially available zirconium xylenol orange reagent was used for determining fluoride concentration. A software program was developed to use with the phone for recording and analyzing the RGB color of the picture. Linear range for fluoride estimation was 0–2 mg l{sup −1}. Around 200 samples, which consisted of laboratory prepared as well as field samples collected from different locations in Karnataka, India, were tested with Akvo Caddisfly. The results showed a significant positive correlation between Ion Selective Electrode (ISE) method and Akvo Caddisfly (Phones A, B and C), with correlation coefficient ranging between 0.9952 and 1.000. In addition, there was no significant difference in the mean fluoride content values between ISE and Phone B and C except for Phone A. Thus the smartphone method is economical and suited for groundwater fluoride analysis in the field. - Highlights: • Fluoride is an inorganic pollutant in ground water, affecting human health. • A colorimetric method for measurement of fluoride in drinking water with smartphone • Measurement is by mixing water with zirconyl xylenol orange complex reagent. • Results are comparable with laboratory-based ion selective fluoride electrode method.

  10. [Inhibition of urease by cyclic beta-triketones and fluoride ions].

    Science.gov (United States)

    Tarun, E I; Rubinov, D B; Metelitsa, D I

    2004-01-01

    Competitive inhibition of soybean urease by 11 cyclic beta-triketones was studied in aqueous solutions at pH 7.4 and 36 degrees C. This process was characterized quantitatively by the inhibition constant (Ki), which showed a strong dependence on the structure of organic chelating agents (nickel atoms in urease) and varied from 58.4 to 847 microM. Under similar conditions, the substrate analogue (hydroxyurea) acted as a weak urease inhibitor (Ki = 6.47 mM). At 20 degrees C, competitive inhibition of urease with the ligand of nickel atoms (fluoride anion) was pH-dependent. At pH 3.85-6.45, the value of Ki for the process ranged from 36.5 to 4060 microM. Three nontoxic cyclic beta-triketones with Ki values of 58.4, 71.4, and 88.0 microM (36 degrees C) were the most potent inhibitors of urease. Their efficacy was determined by the presence of three >C=O- groups in the molecule and minimum steric hindrances to binding with metal sites in soybean urease.

  11. Interaction of singly and multiply charged ions with a lithium-fluoride surface

    CERN Document Server

    Wirtz, L

    2001-01-01

    Charge transfer between slow ions and an ionic crystal surface still poses a considerable challenge to theory due to the intrinsic many-body character of the system. For the neutralization of multiply charged ions in front of metal surfaces, the Classical Over the Barrier (COB) model is a widely used tool. We present an extension of this model to ionic crystal surfaces where the localization of valence electrons at the anion sites and the lack of cylindrical symmetry of the ion-surface system impede a simple analytical estimate of electron transfer rates. We use a classical trajectory Monte Carlo approach to calculate electron transfer rates for different charge states of the projectile ion. With these rates we perform a Monte Carlo simulation of the neutralization of slow Ne10+ ions in vertical incidence on an LiF surface. Capture of one or several electrons may lead to a local positive charge up of the surface. The projectile dynamics depends on the balance between the repulsion due to this charge and the a...

  12. In Vitro Inhibition of Enamel Demineralisation by Fluoride-releasing Restorative Materials and Dental Adhesives.

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Koliniotou-Koumpia, Eugenia; Helvatzoglou-Antoniades, Maria; Kotsanos, Nikolaos

    2016-01-01

    To determine the ability of 5 contemporary fluoride-releasing restoratives and 3 fluoride-releasing adhesives to inhibit enamel demineralisation surrounding restorations, and the associations between inhibition and the levels of fluoride released from these materials. Five fluoride-releasing restoratives (Fuji IX GP, Ketac N100, Dyract Extra, Beautifil II and Wave) and 3 fluoride-releasing adhesives (Stae, Prime & Bond NT and Fluoro Bond II) were investigated. Eight disks of each material were prepared. Fluoride release was measured daily using a fluoride-ion-selective electrode for 15 days. Twenty-four cavities for each group were restored with a restorative and an adhesive. Specimens were subjected to thermal stress and stored for 30 days in saline solution. After a 15-day pH-cycling regimen, two 150-μm-thick sections were derived from each specimen. Enamel lesion depth was measured at 0, 100, and 200 μm from each restoration's margin via polarised light microscopy. Of the restoratives investigated, Fuji IX GP released the most fluoride. The fluoride-releasing restoratives tested exhibited shallower enamel lesions than did the control group at all distances tested (p enamel lesion depth than did the other experimental materials. The depths of enamel lesions did not differ significantly when comparing restoratives applied with a fluoride-releasing adhesive with those applied with a non-fluoride-releasing adhesive. The fluoride-releasing materials tested reduced enamel demineralisation but to different extents, depending on their levels of fluoride release. Fluoride-releasing adhesives did not influence enamel lesion formation.

  13. An entropic mechanism of generating selective ion binding in macromolecules.

    Directory of Open Access Journals (Sweden)

    Michael Thomas

    Full Text Available Several mechanisms have been proposed to explain how ion channels and transporters distinguish between similar ions, a process crucial for maintaining proper cell function. Of these, three can be broadly classed as mechanisms involving specific positional constraints on the ion coordinating ligands which arise through: a "rigid cavity", a 'strained cavity' and 'reduced ligand fluctuations'. Each operates in subtly different ways yet can produce markedly different influences on ion selectivity. Here we expand upon preliminary investigations into the reduced ligand fluctuation mechanism of ion selectivity by simulating how a series of model systems respond to a decrease in ligand thermal fluctuations while simultaneously maintaining optimal ion-ligand binding distances. Simple abstract-ligand models, as well as simple models based upon the ion binding sites in two amino acid transporters, show that limiting ligand fluctuations can create ion selectivity between Li(+, Na(+ and K(+ even when there is no strain associated with the molecular framework accommodating the different ions. Reducing the fluctuations in the position of the coordinating ligands contributes to selectivity toward the smaller of two ions as a consequence of entropic differences.

  14. The Detection Limit of Fluoride With Ion Chromatography%离子色谱法中氟化物检出限确定

    Institute of Scientific and Technical Information of China (English)

    李石

    2013-01-01

      根据离子色谱法检出限定义,运用离子色谱仪反复测定水中氟离子检出限,对不同定义检出限进行推算并比较,各项结果满足JJG823-1993《离子色谱仪检定规程》。%The detection limits of fluoride under different conditions were repeatedly determined with ion chromatography, and the detection limits were calculated and compared. The results met the demand of JJG823-1993 the verification regulation for ion chromatography.

  15. Synthesis and Characterization of Templated Ion Exchange Resins for the Selective Complexation of Actinide Ions

    Energy Technology Data Exchange (ETDEWEB)

    Uy, O. Manual

    2001-03-01

    The purpose of this research is to develop a polymeric extractant for the selective complexation of uranyl ions (and subsequently other actinyl and actinide ions) from aqueous solutions (lakes, streams, waste tanks and even body fluids). Chemical insights into what makes a good complexation site will be used to synthesize reagents tailor-made for the complexation of uranyl and other actinide ions. These insights, derived from studies of molecular recognition include ion coordination number and geometry, ionic size and ionic shape, as well as ion to ligand thermodynamic affinity. Selectivity for a specific actinide ion will be obtained by providing the polymers with cavities lined with complexing ligands so arranged as to match the charge, coordination number, coordination geometry, and size of the actinide metal ion. These cavity-containing polymers will be produced by using a specific ion (or surrogate) as a template around which monomeric complexing ligands will be polymerized. The complexing ligands will be ones containing functional groups known to form stable complexes with a specific ion and less stable complexes with other cations. Prior investigator's approaches for making templated resins for metal ions have had marginal success. We have extended and amended these methodologies in our work with Pb(II) and uranyl ion, by changing the order of the steps, by the inclusion of sonication, by using higher complex loading, and the selection of functional groups with better complexation constants. This has resulted in significant improvements to selectivity. The unusual shape of the uranyl ion suggests that this approach will result in even greater selectivities than already observed for Pb(II). Preliminary data obtained for uranyl templated polymers shows unprecedented selectivity and has resulted in the first ion selective electrode for uranyl ion.

  16. In vitro fluoride release from a different kind of conventional and resin modified glass-ionomer cements.

    Science.gov (United States)

    Selimović-Dragaš, Mediha; Hasić-Branković, Lajla; Korać, Fehim; Đapo, Nermin; Huseinbegović, Amina; Kobašlija, Sedin; Lekić, Meliha; Hatibović-Kofman, Šahza

    2013-08-01

    Fluoride release is important characteristic of glass-ionomer cements. Quantity of fluoride ions released from the glass-ionomer cements has major importance in definition of their biological activity. The objectives of this study were to define the quantity of fluoride ions released from the experimental glass-ionomer cements and to define the effect of fluoride ions released from the experimental glass-ionomer cements on their cytotoxicity. Concentrations of the fluoride ions released in the evaluated glass-ionomer cements were measured indirectly, by the fluoride-selective WTW, F500 electrode potential, combined with reference R503/D electrode. Statistical analyses of F-ion concentrations released by all glass-ionomers evaluated at two time points, after 8 and after 24 hours, show statistically higher fluoride releases from RMGICs: Vitrebond, Fuji II LC and Fuji Plus, when compared to conventional glass-ionomer cements: Fuji Triage, Fuji IX GP Fast and Ketac Silver, both after 8 and after 24 hours. Correlation coefficient between concentrations of fluoride ion released by evaluated glass-ionomer cements and cytotoxic response of UMR-106 osteoblast cell-line are relatively high, but do not reach levels of biological significance. Correlation between concentrations of fluoride ion released and cytotoxic response of NIH3T3 mouse fibroblast cell line after 8 hours is high, positive and statistically significant for conventional GICs, Fuji Triage and Fuji IX GP Fast, and RMGIC, Fuji II LC. Statistically significant Correlation coefficient between concentrations of fluoride ion released and cytotoxic response of NIH3T3 cell line after 24 hours is defined for RMGIC Fuji II LC only.

  17. Fluorides and non-fluoride remineralization systems.

    Science.gov (United States)

    Amaechi, Bennett T; van Loveren, Cor

    2013-01-01

    Caries develops when the equilibrium between de- and remineralization is unbalanced favoring demineralization. De- and remineralization occur depending on the degree of saturation of the interstitial fluids with respect to the tooth mineral. This equilibrium is positively influenced when fluoride, calcium and phosphate ions are added favoring remineralization. In addition, when fluoride is present, it will be incorporated into the newly formed mineral which is then less soluble. Toothpastes may contain fluoride and calcium ions separately or together in various compounds (remineralization systems) and may therefore reduce demineralization and promote remineralization. Formulating all these compounds in one paste may be challenging due to possible premature calcium-fluoride interactions and the low solubility of CaF2. There is a large amount of clinical evidence supporting the potent caries preventive effect of fluoride toothpastes indisputably. The amount of clinical evidence of the effectiveness of the other remineralization systems is far less convincing. Evidence is lacking for head to head comparisons of the various remineralization systems. Copyright © 2013 S. Karger AG, Basel.

  18. 50 MeV lithium ion beam irradiation effects in poly vinylidene fluoride (PVDF) polymer

    Indian Academy of Sciences (India)

    A K Srivastava; H S Virk

    2000-12-01

    Irradiation effects of 50 MeV 7Li+3 ion beam induced in bulk PVDF polymer have been studied with respect to their optical, chemical, structural and electrical behaviour by using UV-visible, FT-IR spectroscopy, XRD technique and electrical frequency response using LCR bridge. The ion fluences ranging from 1.27 × 1011 to 2.15 × 1013 ions cm–2 have been used to study dose effects of irradiation in PVDF. The recorded UV-visible spectra clearly shows five characteristic peaks at 315, 325, 360, 425 and 600 nm. Due to irradiation, the optical absorption initially decreases but then increases with higher fluences. In the FT-IR spectra, no appreciable change has been observed after irradiation, indicating that this polymer is chemically stable. There is exponential increase in admittance with log of frequency but the effect of irradiation is not quite appreciable. The value of tan and relaxation frequency are changed appreciably due to irradiation. The diffraction pattern of PVDF indicates that this polymer is in semi-crystalline form; a decrease in the crystallinity and crystallite size has been observed due to irradiation.

  19. Ion current rectification inversion in conic nanopores: nonequilibrium ion transport biased by ion selectivity and spatial asymmetry.

    Science.gov (United States)

    Yan, Yu; Wang, Lin; Xue, Jianming; Chang, Hsueh-Chia

    2013-01-28

    We show both theoretically and experimentally that the ion-selectivity of a conic nanopore, as defined by a normalized density of the surface charge, significantly affects ion current rectification across the pore. For weakly selective negatively charged pores, intra-pore ion transport controls the current and internal ion enrichment/depletion at positive/reverse biased voltage (current enters/leaves through the tip, respectively), which is responsible for current rectification. For strongly selective negatively charged pores under positive bias, the current can be reduced by external field focusing and concentration depletion at the tip at low ionic strengths and high voltages, respectively. These external phenomena produce a rectification inversion for highly selective pores at high (low) voltage (ionic strength). With an asymptotic analysis of the intra-pore and external ion transport, we derive simple scaling laws to quantitatively capture empirical and numerical data for ion current rectification and rectification inversion of conic nanopores.

  20. Histopathological changes of renal tissue following sodium fluoride administration in two consecutive generations of mice. Correlation with the urinary elimination of fluoride.

    Science.gov (United States)

    Dimcevici Poesina, Nicoleta; Bălălău, Cristian; Nimigean, Vanda Roxana; Nimigean, Victor; Ion, Ion; Baconi, Daniela; Bârcă, Maria; Băran Poesina, Violeta

    2014-01-01

    The present study was designed to investigate the toxic effects (evaluated as histopathological changes) of sodium fluoride on the kidney in two consecutive generations of NMRI mice. An attempt to correlate the toxicity with the urinary elimination of fluoride has been made, as urinary fluoride excretion has been widely used as an indicator of fluoride intake and exposure. Six mixed (males and females) animal groups have been constituted by dividing the populations of mice derived from pregnant females (named "mothers" 0.5 mg sodium fluoride) treated with 0.5 mg sodium fluoride by daily gavage and pregnant females (named "mothers" 0.25 mg sodium fluoride) treated with 0.25 mg sodium fluoride by daily gavage; three types of sodium fluoride treatments were administrated: homeopathic, allopathic-homeopathic and allopathic. When the animals reached the adulthood, by randomization, they were selected in pairs for giving birth to the second generation of mice. No treatments were administrated to the second generation of mice; thus, the urinary elimination of fluoride in the second generation is attributed to exposure at sodium fluoride before birth. The administration of sodium fluoride to the first generation (F1) is realized until the mice reached the adulthood. For the first generation, the urine was collected at three times, every three weeks: at the age of four weeks, seven weeks and 11 weeks; single sampling urine, at the age of four weeks, has been conducted for the second generation. The urine samples have been analyzed using the ion selective electrode method for fluoride. For the histopathological examination, the animals were killed by cervical dislocation; the kidneys were collected in a 10% formalin solution. The preparation of samples for optical microscopy was realized with Hematoxylin-Eosin staining. The results indicate that the elimination of fluoride was similar (at the second evaluation, at 7-week-old of the first generation) for the both generations

  1. Enhancement of etch rate for preparation of nano-sized ion-track membranes of poly(vinylidene fluoride): Effect of pretreatment and high-LET beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Rohani, Rosiah [Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Department of Chemical and Process Engineering, Faculty of Engineering, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Yamaki, Tetsuya [Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)], E-mail: yamaki.tetsuya@jaea.go.jp; Koshikawa, Hiroshi; Takahashi, Shuichi; Hasegawa, Shin; Asano, Masaharu; Maekawa, Yasunari [Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Voss, Kay-Obbe; Trautmann, Christina; Neumann, Reinhard [Materials Research Department, Gesellschaft fur Schwerionenforschung mbH (GSI), Planckstrasse 1, D-64291 Darmstadt (Germany)

    2009-02-15

    We investigated how pretreatment and high-LET beam irradiation affected the ion-track dissolution rate in poly(vinylidene fluoride) (PVDF) films by SEM observations and conductometric analysis in order to develop the preparation methodology of nano-sized ion-track membranes. PVDF thin films irradiated with four types of ion beams were exposed to a 9 mol/dm{sup 3} KOH aqueous solution after their storage in air at 120 deg. C. This heating treatment was found to enhance the etch rate in the latent track, both in the inner core and outer halo regions, without changing that in the bulk, probably due to the formation of parasitic oxidation products facilitating the introduction of the etching agent to improve the etchability. Additionally, the irradiation of heavier higher-LET ions, causing each track to more activated sites (like radicals), was preferable for achieving effective etching.

  2. Is ion channel selectivity mediated by confined water?

    CERN Document Server

    Prada-Gracia, Diego

    2012-01-01

    Ion channels form pores across the lipid bilayer, selectively allowing inorganic ions to cross the membrane down their electrochemical gradient. While the study of ion desolvation free-energies have attracted much attention, the role of water inside the pore is less clear. Here, molecular dynamics simulations of a reduced model of the KcsA selectivity filter indicate that the equilibrium position of Na+, but not of K+, is strongly influenced by confined water. The latter forms a stable complex with Na+, moving the equilibrium position of the ion to the plane of the backbone carbonyls. Almost at the centre of the binding site, the water molecule is trapped by favorable electrostatic interactions and backbone hydrogen-bonds. In the absence of confined water the equilibrium position of both Na+ and K+ is identical. Our observations strongly suggest a previously unnoticed active role of confined water in the selectivity mechanism of ion channels.

  3. Freestanding manganese dioxide nanosheet network grown on nickel/polyvinylidene fluoride coaxial fiber membrane as anode materials for high performance lithium ion batteries

    Science.gov (United States)

    Zhang, Yan; Luo, Zhongping; Xiao, Qizhen; Sun, Tianlei; Lei, Gangtie; Li, Zhaohui; Li, Xiaojing

    2015-11-01

    A novel manganese dioxide (MnO2) nanosheet network grown on nickel/polyvinylidene fluoride (Ni/PVDF) coaxial fiber membrane is successfully fabricated by a three-step route: the polyvinylidene fluoride fiber membrane is prepared by electrospinning method, and then the Ni(shell)/PVDF(core) coaxial fiber membrane with core-shell structure can be obtained by the electroless deposition, and finally the manganese dioxide nanosheet network grown on Ni/PVDF coaxial fiber membrane can be achieved by using a simple hydrothermal treatment. This as-prepared binder-free and flexible composite membrane is directly used as anode for lithium ion batteries. The excellent electrochemical performance of the composite membrane can be attributed to the unique combinative effects of nanosized MnO2 network and conductive Ni/PVDF fiber matrix as well as the porous structure of composite fiber membrane.

  4. Selective Deuterium Ion Acceleration Using the Vulcan PW Laser

    CERN Document Server

    Krygier, AG; Kar, S; Ahmed, H; Alejo, A; Clarke, R; Fuchs, J; Green, A; Jung, D; Kleinschmidt, A; Najmudin, Z; Nakamura, H; Norreys, P; Notley, M; Oliver, M; Roth, M; Vassura, L; Zepf, M; Borghesi, M; Freeman, RR

    2015-01-01

    We report on the successful demonstration of selective acceleration of deuterium ions by target-normal sheath acceleration (TNSA) with a high-energy petawatt laser. TNSA typically produces a multi-species ion beam that originates from the intrinsic hydrocarbon and water vapor contaminants on the target surface. Using the method first developed by Morrison, et al., \\cite{Morrison:POP2012} an ion beam with $>$99$\\%$ deuterium ions and peak energy 28 MeV is produced with a 200 J, 700fs, $>10^{20} W/cm^{2}$ laser pulse by cryogenically freezing heavy water (D$_{2}$O) vapor onto the rear surface of the target prior to the shot. The estimated total yield of deuterium ions in an assumed 10$^{\\circ}$ half-angle cone was 3.0 $\\mu$C (1.9 $\\times 10^{13}$ ions) with 6.6$\\%$ laser-to-deuterium ion energy conversion efficiency.

  5. Synthesis of nanocrystalline mixed metal fluorides in nonaqueous medium

    Indian Academy of Sciences (India)

    Neetu Tyagi; Epsita Ghanti; Nikesh Gupta; N P Lalla; Rajamani Nagarajan

    2009-12-01

    Synthesis of mixed metal fluorides of the general formula, KMF3 (M = Mg, Mn, Co, Ni, Cu and Zn), possessing perovskite structure was investigated in non-aqueous medium. The fluorides were characterized by powder X-ray diffraction, FT–IR spectroscopy, thermal analysis, SEM and TEM. Monophasic cubic phases were obtained for the central metal ions such as Mg, Mn, Co, Ni, and Zn and a tetragonally distorted phase was observed for Cu. The usage of non-aqueous medium is advantageous for the bulk synthesis of these fluorides, since it eliminated the generation and handling of the hazardous HF that has usually been encountered during aqueous preparations. The average crystallite size of the fluorides obtained by this approach was estimated to be in the range of 9–30 nm. SEM micrographs of KZnF3 showed cubic morphology of perovskite phases. TEM studies on KCuF3 confirmed the presence of tetragonal distortion. The fluoride content was determined by titrimetry and found to be nearly stoichiometric. Some of these fluorides were found to be thermally stable up to 225°C in air. These fluorides were employed as fluorinating agents in organic fluorination reactions, thereby suggesting their possible utilization for selective fluorination of aliphatic and aromatic hydrofluorocarbons (HFCs) that are industrially relevant.

  6. Experimental and theoretical study of urea and thiourea based new colorimetric chemosensor for fluoride and acetate ions

    Science.gov (United States)

    Saikia, Eramoni; Borpuzari, Manash Protim; Chetia, Bolin; Kar, Rahul

    2016-01-01

    Two new anion receptors 1,1-(4-nitro-1,2-phenylene) bis(3-phenylurea) (1) and 1,1-(4-nitro-1,2-phenylene) bis(3-phenylthiourea) (2) have been reported here. The binding and colorimetric sensing properties of receptors 1 and 2 with different anions were investigated by naked-eye, 1H-NMR and UV-Vis spectroscopy. They showed effective and selective binding with two biologically important anions F- and CH3COO-, in presence of other anions, such as Cl-, Br-, I-, NO2-, ClO4-, HSO4-, H2PO4-, N3-, CN- in acetonitrile. The relative binding mode of fluoride and acetate anions towards receptors 1 and 2 were studied using density functional theory (DFT), in gas phase and in acetonitrile solvent. Computational studies revealed that receptor 1 formed complexes by two intermolecular hydrogen bonds while receptor 2 by three intermolecular hydrogen bonds. In addition, time dependent DFT (TD-DFT) calculations qualitatively match the experimental UV-Vis spectra.

  7. The impact of stannous, fluoride ions and its combination on enamel pellicle proteome and dental erosion prevention.

    Directory of Open Access Journals (Sweden)

    A A Algarni

    Full Text Available To compare the effects of stannous (Sn and fluoride (F ions and their combination on acquired enamel pellicle (AEP protein composition (proteome experiment, and protection against dental erosion (functional experiment.In the proteome experiment, bovine enamel specimens were incubated in whole saliva supernatant for 24h for AEP formation. They were randomly assigned to 4 groups (n=10, according to the rinse treatment: Sn (800ppm/6.7mM, SnCl2, F (225ppm/13mM, NaF, Sn and F combination (Sn+F and deionized water (DIW, negative control. The specimens were immersed 3× in the test rinses for 2min, 2h apart. Pellicles were collected, digested, and analyzed for protein content using liquid chromatography electrospray ionization tandem mass spectrometry. In the functional experiment, bovine enamel specimens (n=10 were similarly treated for pellicle formation. Then, they were subjected to a five-day erosion cycling model, consisting of 5min erosive challenges (15.6 mM citric acid, pH 2.6, 6×/d and 2min treatment with the rinses containing Sn, F or Sn+F (3×/d. Between the treatments, all specimens were incubated in whole saliva supernatant. Surface loss was determined by profilometry.Our proteome approach on bovine enamel identified 72 proteins that were common to all groups. AEP of enamel treated with Sn+F demonstrated higher abundance for most of the identified proteins than the other groups. The functional experiment showed reduction of enamel surface loss for Sn+F (89%, Sn (67% and F (42% compared to DIW (all significantly different, p<0.05.This study highlighted that anti-erosion rinses (e.g. Sn+F can modify quantitatively and qualitatively the AEP formed on bovine enamel. Moreover, our study demonstrated a combinatory effect that amplified the anti-erosive protection on tooth surface.

  8. Adsorption Kinetics for the Removal of Fluoride from Aqueous Solution by Activated Carbon Adsorbents Derived from the Peels of Selected Citrus Fruits

    Directory of Open Access Journals (Sweden)

    C. Chakrapani

    2010-01-01

    Full Text Available Activated carbons (ACs were prepared from the peels of Citrus documana, Citrus medica and Citrus aurantifolia fruits. Adsorption of fluoride onto these activated carbons was investigated. Effect of contact time in the removal of fluoride from aqueous solution at neutral pH was studied. Five kinetic models; the pseudo first- and second-order equations, intraparticle diffusion, pore diffusion and the Elovich equation, were selected to follow adsorption process. Adsorption of fluoride onto adsorbents could be described by pseudo second-order equation. Kinetic parameters; rate constants, equilibrium adsorption capacities and correlation coefficients, for each kinetic equation were calculated and discussed. The good fitting of kinetic data to pore diffusion and Elovich equations indicate that pore diffusion plays a vital role in controlling the rate of the reaction.

  9. Prevalence of dental fluorosis in relation with different fluoride levels in drinking water among school going children in Sarada tehsil of Udaipur district, Rajasthan

    Directory of Open Access Journals (Sweden)

    B U Sarvaiya

    2012-01-01

    Full Text Available Aim: To estimate the prevalence of dental fluorosis in relation with different fluoride levels in drinking water among school going children of 6-12 years age group. Materials and Methods: Dental fluorosis was recorded using Dean′s index in school children of selected villages. The drinking water samples of all the selected villages were collected in polyethylene bottles and the fluoride content of these samples was determined by fluoride ion selective method using Orion microprocessor analyser. Results: The overall prevalence of dental fluorosis was found to be 69.84%. An increase in the community fluorosis index (CFI with corresponding increase in water fluoride content was found. Conclusion: There was an increase in prevalence of dental fluorosis with a corresponding increase in water fluoride content from 0.8 ppm to 4.1 ppm. A significantly strong positive correlation was found between CFI and fluoride concentration in drinking water.

  10. Prevalence of dental fluorosis in relation with different fluoride levels in drinking water among school going children in Sarada tehsil of Udaipur district, Rajasthan.

    Science.gov (United States)

    Sarvaiya, B U; Bhayya, D; Arora, R; Mehta, D N

    2012-01-01

    To estimate the prevalence of dental fluorosis in relation with different fluoride levels in drinking water among school going children of 6-12 years age group. Dental fluorosis was recorded using Dean's index in school children of selected villages. The drinking water samples of all the selected villages were collected in polyethylene bottles and the fluoride content of these samples was determined by fluoride ion selective method using Orion microprocessor analyser. The overall prevalence of dental fluorosis was found to be 69.84%. An increase in the community fluorosis index (CFI) with corresponding increase in water fluoride content was found. There was an increase in prevalence of dental fluorosis with a corresponding increase in water fluoride content from 0.8 ppm to 4.1 ppm. A significantly strong positive correlation was found between CFI and fluoride concentration in drinking water.

  11. Profile of Fluoride Release from a Nanohybrid Composite Resin

    Directory of Open Access Journals (Sweden)

    Raquel Assed Bezerra Silva

    2015-02-01

    Full Text Available The aim of this study was to evaluate in vitro the amount and profile of fluoride release from a fluoride-containing nanohybrid composite resin (Tetric® N-Ceram by direct potentiometry. Thirty specimens (5 mm diameter x 3 mm high; n=10/material were made of Tetric® N-Ceram, Vitremer® resin-modified glass ionomer cement (RMGIC (positive control or Filtek® Z350 nanofill composite resin (negative control. The specimens were stored individually in plastic tubes containing 1 mL of artificial saliva at 37°C, which was daily renewed during 15 days. At each renewal of saliva, the amount of fluoride ions released in the solution was measured using a fluoride ion-selective electrode with ion analyzer, and the values obtained in mV were converted to ppm (µg/mL. Data were analyzed statistically by ANOVA and Tukey’s post-hoc test at a significance level of 5%. The results showed that the resins Tetric® N-Ceram and Filtek® Z350 did not release significant amounts of fluoride during the whole period of evaluation (p>0.05. Only Vitremer® released significant amounts of fluoride ions during the 15 days of the experiment, with greater release in first 2 days (p0.05. In conclusion, the nanohybrid composite resin Tetric® N-Ceram did not present in vitro fluoride-releasing capacity throughout the 15 days of study.

  12. Fluoride geochemistry of thermal waters in Yellowstone National Park: I. Aqueous fluoride speciation

    Science.gov (United States)

    Deng, Y.; Nordstrom, D.K.; Blaine, McCleskey R.

    2011-01-01

    Thermal water samples from Yellowstone National Park (YNP) have a wide range of pH (1–10), temperature, and high concentrations of fluoride (up to 50 mg/l). High fluoride concentrations are found in waters with field pH higher than 6 (except those in Crater Hills) and temperatures higher than 50 °C based on data from more than 750 water samples covering most thermal areas in YNP from 1975 to 2008. In this study, more than 140 water samples from YNP collected in 2006–2009 were analyzed for free-fluoride activity by ion-selective electrode (ISE) method as an independent check on the reliability of fluoride speciation calculations. The free to total fluoride concentration ratio ranged from 99% at high pH. The wide range in fluoride activity can be explained by strong complexing with H+ and Al3+ under acidic conditions and lack of complexing under basic conditions. Differences between the free-fluoride activities calculated with the WATEQ4F code and those measured by ISE were within 0.3–30% for more than 90% of samples at or above 10−6 molar, providing corroboration for chemical speciation models for a wide range of pH and chemistry of YNP thermal waters. Calculated speciation results show that free fluoride, F−, and major complexes (HF(aq)0">HF(aq)0, AlF2+, AlF2+">AlF2+and AlF30">AlF30) account for more than 95% of total fluoride. Occasionally, some complex species like AlF4-">AlF4-, FeF2+, FeF2+">FeF2+, MgF+ and BF2(OH)2-">BF2(OH)2- may comprise 1–10% when the concentrations of the appropriate components are high. According to the simulation results by PHREEQC and calculated results, the ratio of main fluoride species to total fluoride varies as a function of pH and the concentrations and ratios of F and Al.

  13. Fluoride Rinses, Gels and Foams

    DEFF Research Database (Denmark)

    Twetman, Svante; Keller, Mette K

    2016-01-01

    AIM: The aim of this conference paper was to systematically review the quality of evidence and summarize the findings of clinical trials published after 2002 using fluoride mouth rinses, fluoride gels or foams for the prevention of dental caries. METHODS: Relevant papers were selected after...... an electronic search for literature published in English between 2003 and 2014. The included papers were assessed for their risk of bias and the results were narratively synthesized due to study heterogeneity. The quality of evidence was expressed according to GRADE. RESULTS: A total of 19 papers were included...... (6 on fluoride mouth rinse, 10 on fluoride gel and 3 on fluoride foam); 6 had a low risk of bias while 2 had a moderate risk. All fluoride measures appeared to be beneficial in preventing crown caries and reversing root caries, but the quality of evidence was graded as low for fluoride mouth rinse...

  14. Polyvinylidene fluoride membrane by novel electrospinning system for separator of Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Cuiru [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Jia, Zhidong; Guan, Zhicheng; Wang, Liming [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China)

    2009-04-01

    The remarkable characteristics of nanofibers mats electrospun are large surface area to volume ratio and high porosity, which are crucial to increase the ionic conductivity of membrane full of liquid electrolyte, in this aspect, electrospinning is prior to the other methods, such as dry method, wet method, etc. Therefore, fabricating the separator of Li-ion batteries by electrospinning is potential and promising. The PVDF membranes were fabricated by electrospinning. The experiment demonstrated that the main deficiency in the fabricating separators process by electrospinning was low mechanical property, which induced partial short circuits inside the cells. Several methods were presented to enhance the mechanical strength. The experiments demonstrated that the higher the solution concentration was, the stronger the mechanical strength was, and the higher the voltage was, the stronger the mechanical strength was. Additionally, the spherical hat collection target instead of conditional plane target was applied in the electrospinning system, as a result, the thickness of the membrane was more uniform and the fiber diameter was also more uniform. Therefore, the charge and discharge capacity of the coin type cell composed of the separator collected by spherical hat target exceeded the plane target, and the electrospinning separators exceeded the commercial polypropylene separator. (author)

  15. Polyvinylidene fluoride membrane by novel electrospinning system for separator of Li-ion batteries

    Science.gov (United States)

    Yang, Cuiru; Jia, Zhidong; Guan, Zhicheng; Wang, Liming

    The remarkable characteristics of nanofibers mats electrospun are large surface area to volume ratio and high porosity, which are crucial to increase the ionic conductivity of membrane full of liquid electrolyte, in this aspect, electrospinning is prior to the other methods, such as dry method, wet method, etc. Therefore, fabricating the separator of Li-ion batteries by electrospinning is potential and promising. The PVDF membranes were fabricated by electrospinning. The experiment demonstrated that the main deficiency in the fabricating separators process by electrospinning was low mechanical property, which induced partial short circuits inside the cells. Several methods were presented to enhance the mechanical strength. The experiments demonstrated that the higher the solution concentration was, the stronger the mechanical strength was, and the higher the voltage was, the stronger the mechanical strength was. Additionally, the spherical hat collection target instead of conditional plane target was applied in the electrospinning system, as a result, the thickness of the membrane was more uniform and the fiber diameter was also more uniform. Therefore, the charge and discharge capacity of the coin type cell composed of the separator collected by spherical hat target exceeded the plane target, and the electrospinning separators exceeded the commercial polypropylene separator.

  16. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    Directory of Open Access Journals (Sweden)

    Richard Sauerheber

    2013-01-01

    Full Text Available The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings.

  17. Physiologic Conditions Affect Toxicity of Ingested Industrial Fluoride

    Science.gov (United States)

    Sauerheber, Richard

    2013-01-01

    The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings. PMID:23840230

  18. Ion Selectivity Mechanism in a Bacterial Pentameric Ligand-Gated Ion Channel

    Energy Technology Data Exchange (ETDEWEB)

    Fritsch, Sebastian M [ORNL; Ivanov, Ivaylo N [ORNL; Wang, Hailong [Mayo Clinic College of Medicine; Cheng, Xiaolin [ORNL

    2011-01-01

    The proton-gated ion channel from Gloeobacter violaceus (GLIC) is a prokaryotic homolog of the eukaryotic nicotinic acetylcholine receptor (nAChR) that responds to the binding of neurotransmitter acetylcholine and mediates fast signal transmission. Recent emergence of a high resolution crystal structure of GLIC captured in a potentially open state allowed detailed, atomic-level insight into ion conduction and selectivity mechanisms in these channels. Herein, we have examined the barriers to ion conduction and origins of ion selectivity in the GLIC channel by the construction of potential of mean force (PMF) profiles for sodium and chloride ions inside the transmembrane region. Our calculations reveal that the GLIC channel is open for a sodium ion to transport, but presents a ~10 kcal/mol free energy barrier for a chloride ion, which arises primarily from the unfavorable interactions with a ring of negatively charged glutamate residues (E-2 ) at the intracellular end and a ring of hydrophobic residues (I9 ) in the middle of the transmembrane domain. Our collective findings further suggest that the charge selection mechanism can, to a large extent, be attributed to the narrow intracellular end and a ring of glutamate residues in this position their strong negative electrostatics and ability to bind cations. By contrast, E19 at the extracellular entrance only plays a minor role in ion selectivity of GLIC. In addition to electrostatics, both ion hydration and protein dynamics are found to be crucial for ion conduction as well, which explains why a chloride ion experiences a much greater barrier than a sodium ion in the hydrophobic region of the pore.

  19. Transition-state structure for the quintessential SN2 reaction of a carbohydrate: reaction of α-glucopyranosyl fluoride with azide ion in water.

    Science.gov (United States)

    Chan, Jefferson; Sannikova, Natalia; Tang, Ariel; Bennet, Andrew J

    2014-09-03

    We report that the SN2 reaction of α-d-glucopyranosyl fluoride with azide ion proceeds through a loose (exploded) transition-state (TS) structure. We reached this conclusion by modeling the TS using a suite of five experimental kinetic isotope effects (KIEs) as constraints for the calculations. We also report that the anomeric (13)C-KIE is not abnormally large (k12/k13 = 1.024 ± 0.006), a finding which is at variance with the previous literature value (Zhang et al. J. Am. Chem. Soc. 1994, 116, 7557).

  20. 离子色谱法测定饮用水中氟化物的含量%Determining Fluoride Content in Drinking Water Using Ion Chromatography

    Institute of Scientific and Technical Information of China (English)

    郭丽

    2013-01-01

    The author discussed methods of determining fluoride content in drinking water using ion chromatography, and ob-tained ideal results: detection limit 0.003 mg/L, relative standard deviation under 2.0% and recovery rate 93.7%~110%.%  探讨了用离子色谱法测定饮用水中氟化物含量的方法,此方法的检出限为0.003 mg/L,相对标准偏差在2.0%以下,回收率为93.7%~110%,得出理想结果.

  1. Designer ligands: The search for metal ion selectivity

    Directory of Open Access Journals (Sweden)

    Perry T. Kaye

    2011-03-01

    Full Text Available The paper reviews research conducted at Rhodes University towards the development of metal-selective ligands. The research has focused on the rational design, synthesis and evaluation of novel ligands for use in the formation of copper complexes as biomimetic models of the metalloenzyme, tyrosinase, and for the selective extraction of silver, nickel and platinum group metal ions in the presence of contaminating metal ions. Attention has also been given to the development of efficient, metal-selective molecular imprinted polymers.

  2. Synthesis of alginate bioencapsulated nano-hydroxyapatite composite for selective fluoride sorption.

    Science.gov (United States)

    Pandi, Kalimuthu; Viswanathan, Natrayasamy

    2014-11-04

    This article focuses on the development of eco-friendly adsorbent by alginate (Alg) bioencapsulating nano-hydroxyapatite (n-HAp) namely n-HApAlg composite for defluoridation studies in batch mode. n-HAp powder utilized as a promising defluoridating material, but it causes a significant pressure drop during field applications. To overcome such technological bottlenecks, n-HApAlg composite was synthesized. The defluoridation capacity (DC) of synthesized n-HApAlg composite possesses an enhanced DC of 3870 mg F(-)/kg when compared to n-HAp and calcium alginate (CaAlg) composite which possess DC of 1296 and 680 mg F(-)/kg, respectively. The biocomposite features were characterized using FTIR and SEM with EDAX analysis. The various adsorption influencing parameters like contact time, pH, co-anions, initial fluoride concentration and temperature were optimized. The adsorption process was enlightened by various isotherms and kinetic models. The suitability of the biocomposite at field conditions was also tested.

  3. Cross-Selectivity Enhancement of Poly(vinylidene fluoride-hexafluoropropylene-Based Sensor Arrays for Detecting Acetone and Ethanol

    Directory of Open Access Journals (Sweden)

    Ali Daneshkhah

    2017-03-01

    Full Text Available Two methods for cross-selectivity enhancement of porous poly(vinylidene fluoride-hexafluoropropylene (PVDF-HFP/carbon black (CB composite-based resistive sensors are provided. The sensors are tested with acetone and ethanol in the presence of humid air. Cross-selectivity is enhanced using two different methods to modify the basic response of the PVDF-HFP/CB sensing platform. In method I, the adsorption properties of PVDF-HFP/CB are altered by adding a polyethylene oxide (PEO layer or by treating with infrared (IR. In method II, the effects of the interaction of acetone and ethanol are enhanced by adding diethylene carbonate (DEC or PEO dispersed in DEC (PEO/DEC to the film. The results suggest the approaches used in method I alter the composite ability to adsorb acetone and ethanol, while in method II, they alter the transduction characteristics of the composite. Using these approaches, sensor relative response to acetone was increased by 89% compared with the PVDF-HFP/CB untreated film, whereas sensor relative response to ethanol could be decreased by 57% or increased by 197%. Not only do these results demonstrate facile methods for increasing sensitivity of PVDF-HFP/CB film, used in parallel they demonstrate a roadmap for enhancing system cross-selectivity that can be applied to separate units on an array. Fabrication methods, experimental procedures and results are presented and discussed.

  4. Prevalence of fluorosis and identification of fluoride endemic areas in Manur block of Tirunelveli District, Tamil Nadu, South India

    Science.gov (United States)

    Gopalakrishnan, Subarayan Bothi; Viswanathan, Gopalan; Siva Ilango, S.

    2012-12-01

    Prevalence of fluorosis is mainly due to the consumption of more fluoride through drinking water. It is necessary to identify the fluoride endemic areas to adopt remedial measures for the people under the risk of fluorosis. The objectives of this study were to identify the exact location of fluoride endemic areas in Manur block of Tirunelveli District and to estimate fluoride exposure level through drinking water for different age groups. Identification of fluoride endemic areas was performed through Isopleth and Google earth mapping techniques. Fluoride level in drinking water samples was estimated by fluoride ion selective electrode method. A systematic clinical survey conducted in 19 villages of Manur block revealed the rate of prevalence of fluorosis. From this study, it has been found that Alavanthankulam, Melapilliyarkulam, Keezhapilliyarkulam, Nadupilliyarkulam, Keezhathenkalam and Papankulam are the fluoride endemic villages, where the fluoride level in drinking water is above 1 mg/l. Consumption of maximum fluoride exposure levels of 0.30 mg/kg/day for infants, 0.27 mg/kg/day for children and 0.15 mg/kg/day for adults were found among the respective age group people residing in high fluoride endemic area. As compared with adequate intake level of fluoride of 0.01 mg/kg/day for infants and 0.05 mg/kg/day for other age groups, the health risk due to excess fluoride intake to the people of Alavanthankulam and nearby areas has become evident. Hence the people of these areas are advised to consume drinking water with optimal fluoride to avoid further fluorosis risks.

  5. Effect of fluoride ions on the optical properties of Eu{sup 3+}:PbF{sub 2} nanocrystals embedded into sol–gel host materials

    Energy Technology Data Exchange (ETDEWEB)

    Szpikowska-Sroka, Barbara, E-mail: barbara.szpikowska-sroka@us.edu.pl; Pawlik, Natalia; Żur, Lidia; Czoik, Rozalia; Goryczka, Tomasz; Pisarski, Wojciech A.

    2016-05-01

    In this research, the effects of fluoride ions concentration on luminescence properties of Eu{sup 3+}:PbF{sub 2} nanocrystals in silicate sol–gel materials have been investigated. Optical and structural properties of Eu{sup 3+}:PbF{sub 2} nanocrystals have been examined using X-ray diffraction analysis (XRD) and luminescence spectroscopy. Formation of the cubic β-PbF{sub 2} nanocrystalline phase was confirmed. The crystal size was estimated using Scherrer's equation and Williamson-Hall formula. The optical behavior of Eu{sup 3+} ions in studied materials is strongly dependent on amount of incorporated fluorides in the host lattice and the optimal concentration about 3.0 mass. % give the more intense emission of Eu{sup 3+}. The luminescence spectra showed the characteristic orange-red emission due to the {sup 5}D{sub 0} → {sup 7}F{sub 1} and {sup 5}D{sub 0} → {sup 7}F{sub 2} electron transitions, respectively. The luminescence intensity ratio R (I({sup 5}D{sub 0} → {sup 7}F{sub 2})/I({sup 5}D{sub 0} → {sup 7}F{sub 1})) and luminescence lifetimes for the {sup 5}D{sub 0} excited state of Eu{sup 3+} ions were determined for each sample before and after heat treatment process. Obtained results indicate the partially incorporation of Eu{sup 3+} ions into β-PbF{sub 2} nanocrystalline phase during ceramization process. - Highlights: • The effect of fluoride ions concentration on luminescence properties was studied. • Formation of cubic β-PbF{sub 2} nanocrystalline phase was confirmed. • The crystal size was estimated using Scherrer's and Williamson-Hall methods. • Luminescence decay curves of the investigated sol–gel glasses were examined. • The results indicate incorporation of Eu{sup 3+} ions into nanocrystalline phase.

  6. Metal Ion Selectivity of Kojate Complexes: A Theoretical Study

    Directory of Open Access Journals (Sweden)

    Sarita Singh

    2013-01-01

    Full Text Available Density functional calculations have been performed on four-coordinate kojate complexes of selected divalent metal ions in order to determine the affinity of the metal ions for the kojate ion. The complexation reactions are characterized by high energies, showing that they are highly exothermic. It is found that Ni(II exhibits the highest affinity for the kojate ion, and this is attributed to the largest amount of charge transfer from the ligand to the metal ion. The Ni(II complex has distorted square planar structure. The HOMOs and LUMOs of the complexes are also discussed. All complexes display a strong band at ~1500 cm−1 corresponding to the stretching frequency of the weakened carbonyl bond. Comparison of the complexation energies for the two steps shows that most of the complexation energy is realized in the first step. The energy released in the second step is about one-third that of the first step.

  7. [Fluoride content in potable water and drinks. Connection with dental caries prevention and dental fluorosis].

    Science.gov (United States)

    Borinskiĭ, Iu N; Rumiantsev, V A; Borinskaia, E Iu; Beliaev, V V

    2009-01-01

    Content of fluoride by ion selective electrode in potable water (municipal water supply, bottled, from draw-wells and springs), in juices of industrial and compotes of domestic preparation, in drinks of various grades of the tea made by water with unequal contents of fluorine was analyzed. Fluoride entered organism of the population in non-control mode more often in minimum quantities that explained, in certain measures a wide caries incidence. Granting of the information upon concentration of fluorides in potable water, juices and drinks used by population would allow people to adjust this microelement intake in the organism with the purpose of preventing of dental caries and fluorosis.

  8. DFT/TDDFT investigation of the modulation of photochromic properties in an organoboron-based diarylethene by fluoride ions.

    Science.gov (United States)

    Liu, Shujuan; Sun, Shi; Wang, Chuanming; Zhao, Qiang; Sun, Huibin; Li, Fuyou; Fan, Quli; Huang, Wei

    2011-02-07

    The diarylethene derivative 1,2-bis-(5'-dimesitylboryl-2'-methylthieny-3'-yl)-cyclopentene (1) containing dimesitylboryl groups is an interesting photochromic material. The dimesitylboryl groups can bind to F(-), which tunes the optical and electronic properties of the diarylethene compound. Hence, the diarylethene derivative 1 containing dimesitylboryl groups is sensitive to both light and F(-), and its photochromic properties can be tuned by a fluoride ion. Herein, we studied the substituent effect of dimesitylboron groups on the optical properties of both the closed-ring and open-ring isomers of the diarylethene molecule by DFT/TDDFT calculations and found that these methods are reliable for the determination of the lowest singlet excitation energies of diarylethene compounds. The introduction of dimesitylboron groups to the diarylethene compound can elongate its conjugation length and change the excited-state properties from π→π* transition to a charge-transfer state. This explains the modulation of photochromic properties through the introduction of dimesitylboron groups. Furthermore, the photochromic properties can be tuned through the binding of F(-) to a boron center and the excited state of the diarylethene compound is changed from a charge-transfer state to a π→π* transition. Hence, a subtle control of the photochromic spectroscopic properties was realized. In addition, the changes of electronic characteristics by the isomerization reaction of diarylethene compounds were also investigated with theoretical calculations. For the model compound 2 without dimesitylboryl groups, the closed-ring isomer has better hole- and electron-injection abilities, as well as higher charge-transport rates, than the open-ring isomer. The introduction of dimesitylboron groups to diarylethene can dramatically improve the charge-injection and -transport abilities. The closed isomer of compound 1 (1 C) has the best hole- and electron-injection abilities, whereas the

  9. Tuning the ion selectivity of two-pore channels

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiangtao; Zeng, Weizhong; Jiang, Youxing (UTSMC)

    2017-01-17

    Organellar two-pore channels (TPCs) contain two copies of a Shaker-like six-transmembrane (6-TM) domain in each subunit and are ubiquitously expressed in plants and animals. Interestingly, plant and animal TPCs share high sequence similarity in the filter region, yet exhibit drastically different ion selectivity. Plant TPC1 functions as a nonselective cation channel on the vacuole membrane, whereas mammalian TPC channels have been shown to be endo/lysosomal Na+-selective or Ca2+-release channels. In this study, we performed systematic characterization of the ion selectivity of TPC1 from Arabidopsis thaliana (AtTPC1) and compared its selectivity with the selectivity of human TPC2 (HsTPC2). We demonstrate that AtTPC1 is selective for Ca2+ over Na+, but nonselective among monovalent cations (Li+, Na+, and K+). Our results also confirm that HsTPC2 is a Na+-selective channel activated by phosphatidylinositol 3,5-bisphosphate. Guided by our recent structure of AtTPC1, we converted AtTPC1 to a Na+-selective channel by mimicking the selectivity filter of HsTPC2 and identified key residues in the TPC filters that differentiate the selectivity between AtTPC1 and HsTPC2. Furthermore, the structure of the Na+-selective AtTPC1 mutant elucidates the structural basis for Na+ selectivity in mammalian TPCs.

  10. A Method of Determining Selectivity Coefficients Based on the Practical Slope of Ion Selective Electrodes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    It is a problem to be solved that the experimental selectivity coefficients of ion selective electrodes (ISEs) depend on the activity.This paper studied the new method of determining selectivity coefficients.A mixed ion response equation,which was similar to Nicolsky-Eisenman (N-E) equation recommended by IUPAC,was proposed.The equation includes the practical response slope of ISEs to the primary ion and the interfering ion.The selectivity coefficient was defined by the equation instead of the N-E equation.The experimental part of the method is similar to that based on the N-E equation.The values of selectivity coefficients obtained with this method do not depend on the activity whether the electrodes exhibit the Nernst response or non-Nernst response.The feasibility of the new method is illustrated experimentally.

  11. Fluoride Content in Alcoholic Drinks

    OpenAIRE

    Goschorska, Marta; Gutowska, Izabela; Baranowska-Bosiacka, Irena; Ra?, Monika Ewa; Chlubek, Dariusz

    2015-01-01

    The aim of the study was to determine the role of alcoholic drinks as a potential source of dietary fluoride by means of measuring fluoride levels in selected alcoholic drinks available on the Polish market that are also diverse in terms of the percentage content of ethanol. The study was conducted on 48 types of drinks with low, medium, and high alcohol content available on the Polish market and offered by various manufacturers, both Polish and foreign. Fluoride concentrations in individual ...

  12. Spatial distribution mapping of drinking water fluoride levels in Karnataka, India: fluoride-related health effects.

    Science.gov (United States)

    Chowdhury, Chitta R; Shahnawaz, Khijmatgar; Kumari, Divya; Chowdhury, Avidyuti; Bedi, Raman; Lynch, Edward; Harding, Stewart; Grootveld, Martin

    2016-11-01

    (1) To estimate the concentrations of fluoride in drinking water throughout different zones and districts of the state of Karnataka. (2) To investigate the variation of fluoride concentration in drinking water from different sources, and its relationships to daily temperature and rainfall status in the regional districts. (3) To develop an updated fluoride concentration intensity map of the state of Karnataka, and to evaluate these data in the context of fluoride-related health effects such as fluorosis and their prevalence. Aqueous standard solutions of 10, 100 and 1,000 ppm fluoride (F(-)) were prepared with analytical grade Na(+)/F(-) and a buffer; TISAB II was incorporated in both calibration standard and analysis solutions in order to remove the potentially interfering effects of trace metal ions. This analysis was performed using an ion-selective electrode (ISE), and mean determination readings for n = 5 samples collected at each Karnataka water source were recorded. The F(-) concentration in drinking water in Karnataka state was found to vary substantially, with the highest mean values recorded being in the north-eastern zone (1.61 ppm), and the lowest in the south-western one (only 0.41 ppm). Analysis of variance (ANOVA) demonstrated that there were very highly significant 'between-zone' and 'between-districts-within-zones' sources of variation (p water source F(-) levels within this state. The southern part of Karnataka has low levels of F(-) in its drinking water, and may require fluoridation treatment in order to mitigate for dental caries and further ailments related to fluoride deficiency. However, districts within the north-eastern region have contrastingly high levels of fluoride, an observation which has been linked to dental and skeletal fluorosis. This highlights a major requirement for interventional actions in order to ensure maintenance of the recommended range of fluoride concentrations (0.8-1.5 ppm) in Karnataka's drinking water

  13. Aquifer wise seasonal variations and spatial distribution of major ions with focus on fluoride contamination-Pandharkawada block, Yavatmal district, Maharashtra, India.

    Science.gov (United States)

    Pandith, Madhnure; Malpe, D B; Rao, A D; Rao, P N

    2016-02-01

    Seasonal variations in groundwater reveal lesser concentrations of major ions except NO3(-) during post-monsoon seasons in shallow aquifers as compared to deeper aquifers. The F(-) concentration from deeper aquifers is high in both seasons and shows a moderate positive relationship with weathering depth and is >5 mg/L in compound lava flow. Groundwater is mainly a Ca-HCO3 type in shallow aquifers and mixed type in deeper aquifers. Fluoride shows a positive correlation with pH, Na(+), HCO3(-) in shallow aquifers and an inverse correlation with Ca(2+) and HCO3(-) from deeper aquifers in both seasons. Approximately 45% of the samples are not suitable for drinking from both aquifers but suitable for irrigation purposes. Rock-water interaction, moderate alkalinity, sluggish movement, and higher residence time are the main causes for high F(-) in deeper aquifers as compared to shallow aquifers. As recommendations, drinking water requirement may be met from shallow aquifers/surface water and fluoride rich groundwater for other purposes. Most effective defluoridation techniques like ion exchange and reverse osmosis may be adopted along with integrated fluorosis mitigation measures and rooftop rainwater harvesting. Supplementary calcium and phosphorous rich food should be provided to children and creating awareness about safe drinking water habits, side effects of high F(-), and NO3(-) rich groundwater, improving oral hygiene conditions are other measures.

  14. Synthesis of novel calix[4]crown telomers and selective extraction of cesium ions

    Institute of Scientific and Technical Information of China (English)

    Hai Bing Li; Yuan Yin Chen; De Jun Xiong; Jun Yan Zhan; Cui Ping Han

    2007-01-01

    p-tert-Butylcalix[4]diazacrown-4 telomer, which contains hard and soft ion binding sites, was synthesized. It exhibited high selectivity toward cesium ions. The binding sites may complex alkali metal ions selectively.

  15. Molecular anions sputtered from fluorides

    CERN Document Server

    Gnaser, H

    2002-01-01

    The emission of negatively charged ions from different fluoride samples (LiF, CaF sub 2 , LaF sub 3 and HfF sub 4) induced by sputtering with a 14.5-keV Cs sup + ion beam was studied. Sputtered ions were detected in a high-sensitivity double-focusing mass spectrometer. In particular, the possible existence of small doubly charged negative molecular ions was investigated. But whereas singly charged species of the general type MF sub n sup - (where M represents a metal atom) were detected with high abundances, stable dianions were observed in an unambiguous way only for one molecule: HfF sub 6 sup 2 sup -. The flight time through the mass spectrometer of approx 35 mu s establishes a lower limit with respect to the intrinsic lifetime of this doubly charged ion. For singly charged anions abundance distributions and, in selected cases, emission-energy spectra were recorded. For two ion species (Ca sup - and HfF sub 5 sup -) isotopic fractionation effects caused by the (velocity dependent) ionization process were d...

  16. A porous poly(vinylidene fluoride) gel electrolyte for lithium ion batteries prepared by using salicylic acid as a foaming agent

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.P. [Department of Material Science, Fudan University, Shanghai 200433 (China); Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Zhang, P.; Li, G.C.; Wu, Y.P. [Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Sun, D.L. [Department of Material Science, Fudan University, Shanghai 200433 (China)

    2009-04-01

    A porous gel polymer electrolyte based on poly(vinylidene fluoride) (PVDF) was for the first time prepared via a foaming technology using salicylic acid as a foaming agent. The pores are evenly distributed with an average diameter of about 400 nm. The results from TG/DTA, XRD and FT-IR show that there are no vesicant residues after the PVDF film was heat-treated at 200 C to get the porous structure. When the film is gelled with liquid electrolyte, the ion conductivity can be up to 4.8 x 10{sup -3} S cm{sup -1} at room temperature and the activation energy for ionic transfer is 10.2 kJ mol{sup -1}. LiCoO{sub 2} cathode also presents good cycling performance. These primary results show great promise for this simple method to prepare porous gel polymer electrolytes for practical application in lithium ion batteries. (author)

  17. Size-controlled synthesis of hierarchical nanoporous iron based fluorides and their high performances in rechargeable lithium ion batteries.

    Science.gov (United States)

    Lu, Yan; Wen, Zhao-yin; Jin, Jun; Wu, Xiang-wei; Rui, Kun

    2014-06-21

    High performance nanostructured iron fluorides with controllable sizes were successfully synthesized using oleylamine as a size tuning agent for the first time. They exhibited excellent cathode performances with large retensive capacities exceeding 200 mA h g(-1) after 50 cycles and outstanding rate performances of nearly 100 mA h g(-1) even at 10 C.

  18. Infrared ion spectroscopy inside a mass-selective cryogenic 2D linear ion trap.

    Science.gov (United States)

    Cismesia, Adam P; Tesler, Larry F; Bell, Matthew R; Bailey, Laura S; Polfer, Nicolas C

    2017-07-27

    We demonstrate operation of the first cryogenic 2D linear ion trap (LIT) with mass-selective capabilities. This trap presents a number of advantages for infrared ion "action" spectroscopy studies, particularly those employing the "tagging/messenger" spectroscopy approach. The high trapping efficiencies, trapping capacities, and low detection limits make 2D LITs a highly suitable choice for low-concentration analytes from scarce biological samples. In our trap, ions can be cooled down to cryogenic temperatures to achieve higher-resolution infrared spectra, and individual ions can be mass selected prior to irradiation for a background-free photodissociation scheme. Conveniently, multiple tagged analyte ions can be mass isolated and efficiently irradiated in the same experiment, allowing their infrared spectra to be recorded in parallel. This multiplexed approach is critical in terms of increasing the duty cycle of infrared ion spectroscopy, which is currently a key weakness of the technique. The compact design of this instrument, coupled with powerful mass selection capabilities, set the stage for making cryogenic infrared ion spectroscopy viable as a bioanalytical tool in small molecule identification. This article is protected by copyright. All rights reserved.

  19. Fluoride and aluminum in teas and tea-based beverages

    Directory of Open Access Journals (Sweden)

    Hayacibara Mitsue Fujimaki

    2004-01-01

    Full Text Available OBJECTIVE: To evaluate fluoride and aluminum concentration in herbal, black, ready-to-drink, and imported teas available in Brazil considering the risks fluoride and aluminum pose to oral and general health, respectively. METHODS: One-hundred and seventy-seven samples of herbal and black tea, 11 types of imported tea and 21 samples of ready-to-drink tea were divided into four groups: I-herbal tea; II-Brazilian black tea (Camellia sinensis; III-imported tea (Camellia sinensis; IV-ready-to-drink tea-based beverages. Fluoride and aluminum were analyzed using ion-selective electrode and atomic absorption, respectively. RESULTS: Fluoride and aluminum levels in herbal teas were very low, but high amounts were found in black and ready-to-drink teas. Aluminum found in all samples analyzed can be considered safe to general health. However, considering 0.07 mg F/kg/day as the upper limit of fluoride intake with regard to undesirable dental fluorosis, some teas exceed the daily intake limit for children. CONCLUSIONS: Brazilian and imported teas made from Camellia sinensis as well as some tea-based beverages are sources of significant amounts of fluoride, and their intake may increase the risk of developing dental fluorosis.

  20. Monitoring of fluoride in water samples using a smartphone.

    Science.gov (United States)

    Levin, Saurabh; Krishnan, Sunderrajan; Rajkumar, Samuel; Halery, Nischal; Balkunde, Pradeep

    2016-05-01

    In several parts of India, groundwater is the only reliable, year round source for drinking water. Prevention of fluorosis, a chronic disease resulting from excess intake of fluoride, requires the screening of all groundwater sources for fluoride in endemic areas. In this paper, the authors present a field deployable colorimetric analyzer based on an inexpensive smartphone embedded with digital camera for taking photograph of the colored solution as well as an easy-fit, and compact sample chamber (Akvo Caddisfly). Phones marketed by different smartphone makers were used. Commercially available zirconium xylenol orange reagent was used for determining fluoride concentration. A software program was developed to use with the phone for recording and analyzing the RGB color of the picture. Linear range for fluoride estimation was 0-2mgl(-1). Around 200 samples, which consisted of laboratory prepared as well as field samples collected from different locations in Karnataka, India, were tested with Akvo Caddisfly. The results showed a significant positive correlation between Ion Selective Electrode (ISE) method and Akvo Caddisfly (Phones A, B and C), with correlation coefficient ranging between 0.9952 and 1.000. In addition, there was no significant difference in the mean fluoride content values between ISE and Phone B and C except for Phone A. Thus the smartphone method is economical and suited for groundwater fluoride analysis in the field.

  1. Determination of Fluoride in Organic and Non-organic Wines.

    Science.gov (United States)

    Paz, Soraya; Jaudenes, Juan Ramón; Gutiérrez, Angel José; Rubio, Carmen; Hardisson, Arturo; Revert, Consuelo

    2016-12-27

    Fluorine is an element of great importance to human health, as it is considered to be an essential element. However, both a deficiency and an excess, it can cause various problems. It is for this reason that values have been established regarding the recommended daily intake (RDI) and acceptable daily intake (ADI). The largest source of incorporation of fluoride is water, but it can be found in other foods and beverages, such as vegetables, tea, and wine. The aim of the study was to establish the fluoride concentration in organic and non-organic wines from different appellations of origin of the Canary Islands and mainland Spain, in order to assess the contribution of fluoride and toxic risk. A total of 53 samples of red, white, and rosé wines, both organic and non-organic, from different appellations of origin were analyzed. They were analyzed by potentiometric determination with ion-selective electrode for fluoride using the method of standard addition. The wines analyzed are within the recommended limits set by the International Organisation of Vine and Wine. RDI is not exceeded for adults, taking into account the data provided by the Spanish Agency for Consumer Affairs, Food Safety and Nutrition on the average consumption of "table wines" in Spain. Fluoride intake from wine poses no risk to the health of adults. The fluoride concentration of organic and non-organic wines is within the range of 0.03 to 0.70 mg/L.

  2. Fluoride and aluminum in teas and tea-based beverages

    Directory of Open Access Journals (Sweden)

    Mitsue Fujimaki Hayacibara

    2004-02-01

    Full Text Available OBJECTIVE: To evaluate fluoride and aluminum concentration in herbal, black, ready-to-drink, and imported teas available in Brazil considering the risks fluoride and aluminum pose to oral and general health, respectively. METHODS: One-hundred and seventy-seven samples of herbal and black tea, 11 types of imported tea and 21 samples of ready-to-drink tea were divided into four groups: I-herbal tea; II-Brazilian black tea (Camellia sinensis; III-imported tea (Camellia sinensis; IV-ready-to-drink tea-based beverages. Fluoride and aluminum were analyzed using ion-selective electrode and atomic absorption, respectively. RESULTS: Fluoride and aluminum levels in herbal teas were very low, but high amounts were found in black and ready-to-drink teas. Aluminum found in all samples analyzed can be considered safe to general health. However, considering 0.07 mg F/kg/day as the upper limit of fluoride intake with regard to undesirable dental fluorosis, some teas exceed the daily intake limit for children. CONCLUSIONS: Brazilian and imported teas made from Camellia sinensis as well as some tea-based beverages are sources of significant amounts of fluoride, and their intake may increase the risk of developing dental fluorosis.

  3. Ion-selective electrodes: historical, mechanism of response, selectivity and concept review

    Directory of Open Access Journals (Sweden)

    Fernandes Julio Cesar Bastos

    2001-01-01

    Full Text Available This paper presents a review of the concepts involved in the working mechanism of the ion-selective electrodes, searching a historical overview, moreover to describe the new advances in the area.

  4. Beyond Conventional Cathode Materials for Lithium-ion Batteries and Sodium-ion Batteries Nickel fluoride conversion materials and P2 type Sodium-ion intercalation cathodes

    Science.gov (United States)

    Lee, Dae Hoe

    The Li-ion battery is one of the most important rechargeable energy storage devices due to its high energy density, long cycle life, and reliable safety. Although the performances of Li-ion batteries have been improved dramatically, the limit in terms of the energy density still needs to be resolved to meet the growing demands for large-scale mobile devices. Choosing the cathode material is the most pivotal issue in achieving higher energy, since the energy density is directly correlated to the specific capacity of the cathode. Intercalation-based cathode materials have been widely utilized in commercial products; however they yield a limited capacity due to restricted crystallographic sites for Li-ions. In this thesis, the NiF2 and NiO doped NiF2/C conversion materials, which display substantially greater capacities, are intensively studied using various synchrotron X-ray techniques and magnetic measurements. The enhanced electronic conductivity of NiO doped NiF2/C is associated with a significant improvement in the reversible conversion reaction. While bimodal Ni nanoparticles are maintained for NiO doped NiF2/C upon the discharge, for pure NiF2 only smaller nanoparticles remain following the 2nd discharge. Based on the electronic conductivity, it is demonstrated that the size of Ni nanoparticles is associated with the conversion kinetics and consequently the reversibility. Although Li-ion batteries offer the highest energy density among all the secondary batteries, the amount of the reserves and the cost associated with the Li sources are still a concern. In the second part of the thesis, P2 type Na2/3[Ni1/3Mn2/3]O2 is investigated to understand the structural stability in the Na-ion batteries. Significantly improved battery performances are obtained by excluding the phase transformation region. In addition, the structural evolution of the P2-Na0.8[Li0.12Ni0.22Mn0.66]O 2 is tracked by in situ technique and revealed no phase transformation during the cycling. It

  5. Rare earth ions enhanced near infrared fluorescence of Ag2S quantum dots for the detection of fluoride ions in living cells.

    Science.gov (United States)

    Ding, Caiping; Cao, Xuanyu; Zhang, Cuiling; He, Tangrong; Hua, Nan; Xian, Yuezhong

    2017-09-28

    In this work, a novel phenomenon was discovered that the fluorescence intensity of silver sulfide quantum dots (Ag2S QDs) could be enhanced in the presence of rare earth ions through aggregation-induced emission (AIE). Based on the strong coordination between rare earth ions and F(-), a facile and label-free strategy was developed for the detection of F(-) in living cells. Ag2S QDs were synthesized using 3-mercaptopropionic acid as sulfur source and stabilizer in aqueous solution. The near infrared (NIR) emitting QDs exhibited excellent photostalilty, high quantum yield and low toxic. Interestingly, the fluorescence intensity of QDs was obviously enhanced upon the addition of various rare earth ions, especially in the presence of Gd(3+). The AIE mechanism was proved via the TEM, zeta potential and dynamic light scattering analysis. Moreover, the coordination between rare earth ions and F(-) could lead to the quenching of fluorescence QDs due to the weakening the AIE. Based on these findings, we developed a highly sensitive and selective method for detection of F(-). The label-free NIR fluorescence probe was successfully used for F(-) bioimaging in live cells.

  6. Fluoride determination in various matrices relevant to nuclear industry: A review

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, R.M.; Mahajan, M.A.; Verma, P.; Shah, D.; Thakur, U.K.; Ramakumar, K.L.; Venugopal, V. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Radioanalytical Chemistry Section

    2007-07-01

    The determination of fluoride from diverse matrices at front and back end of nuclear technology and some studies from this laboratory on optimizations of different experimental parameters differing with multiple fuels and reactor materials, have been reviewed. The most useful techniques such as fluoride ion selective electrode (F-ISE) and ion-chromatography (IC) widely adopted as routine methods for fluoride determination in nuclear industry have been discussed. The effect of various buffer strengths on the response of the fluoride ion selective electrode has been examined. The ion chromatographic studies on mobile phase concentration, medium of sample, sample injection volume etc. to get distinct fluoride peak within optimum time in presence of other anionic species in diverse concentrations have been reported. The results of various sample matrices such as UO{sub 2}, PuO{sub 2}, (U,Pu)O{sub 2}, Pu-alloy, thoria, zircaloy, slag, HLLW, LLLW etc., analyzed after matrix separation using pyrohydrolysis setup, for both solid and liquid samples and without matrix separation by masking potentially interfering ions of liquid samples, have been presented. (orig.)

  7. Selective Gas-Phase Oxidation and Localization of Alkylated Cysteine Residues in Polypeptide Ions via Ion/Ion Chemistry.

    Science.gov (United States)

    Pilo, Alice L; Zhao, Feifei; McLuckey, Scott A

    2016-09-01

    The thiol group in cysteine residues is susceptible to several post-translational modifications (PTMs), including prenylation, nitrosylation, palmitoylation, and the formation of disulfide bonds. Additionally, cysteine residues involved in disulfide bonds are commonly reduced and alkylated prior to mass spectrometric analysis. Several of these cysteine modifications, specifically S-alkyl modifications, are susceptible to gas-phase oxidation via selective ion/ion reactions with periodate anions. Multiply protonated peptides containing modified cysteine residues undergo complex formation upon ion/ion reaction with periodate anions. Activation of the ion/ion complexes results in oxygen transfer from the reagent to the modified sulfur residue to create a sulfoxide functionality. Further activation of the sulfoxide derivative yields abundant losses of the modification with the oxidized sulfur as a sulfenic acid (namely, XSOH) to generate a dehydroalanine residue. This loss immediately indicates the presence of an S-alkyl cysteine residue, and the mass of the loss can be used to easily deduce the type of modification. An additional step of activation can be used to localize the modification to a specific residue within the peptide. Selective cleavage to create c- and z-ions N-terminal to the dehydroalanine residue is often noted. As these types of ions are not typically observed upon collision-induced dissociation (CID), they can be used to immediately indicate where in the peptide the PTM was originally located.

  8. Crystal field splitting of the 4f 5d electronic configuration of Pr 3+ ions in wide band gap fluoride dielectric crystals

    Science.gov (United States)

    Sarantopoulou, E.; Kollia, Z.; Cefalas, A. C.; Semashko, V. V.; Yu. Abdulsabirov, R.; Naumov, A. K.; Korableva, S. L.; Szczurek, T.; Kobe, S.; McGuiness, P. J.

    2002-07-01

    The absorption and the laser-induced fluorescence spectra of Pr 3+ ion in YF 3, LaF 3, KY 3 F 10 and LiLuF 4, single crystal hosts were obtained in the vacuum ultraviolet region of the spectrum. The energy position and the spacing of the levels of the 4f 5d electronic configuration depend on the host matrix. In addition, strong vacuum ultraviolet emission bands were observed, following crystal excitation at 157 nm with the molecular fluorine laser. The emission bands were due to the interconfigurational 4 f 5 d→4 f2 dipole-allowed transitions in Pr 3+ ions, and they were assigned to the transitions between the edge of the lowest Stark component of the 4f 5d electronic configuration and the levels of the 4f 2 electronic configuration. The VUV spectra can be interpreted by applying the crystal field model, and taking into consideration that lanthanide contraction of the 4f n-1 5d electronic configurations of the rare earth ions, and shielding of the positive ion charge from the electrons in the 4f n electronic configuration is taking place. Finally, a new method for monitoring the concentration of the rare earth ions in wide band gap fluoride dielectric crystals in a non-destructive way, by measuring magnetic dipole moments with the vibrating sample magnetometer (VSM) method, is presented for the first time to our knowledge for this type of crystals.

  9. Selective extraction of tantalum fluoride in polyurethane foam; Sorcao seletiva de fluoreto de tantalo em espuma de poliuretano

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Elizabeth de M. Massena; Schwamback, Niomedes; Mantovano, Jose Luiz; Carvalho, Marcelo S. de [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)

    2000-07-01

    The physico-chemical parameters for tantalum fluoride extraction on polyether polyurethane foam (PUF) were investigated focusing on its selective separation from sample matrices of fluoro complexes metals and direct determination on ground PUF by X-ray fluorescence (dispersive wavelength). Tantalum was quantitatively recovered from 0,5 mol/L hydrofluoric acid solution, after 40 minutes mechanical shaking, using batch procedure and 0,1 g PUF. The system allows the presence of sulfuric acid until 2,0 mol/L, shows distribution ratio (D) of about 3,2.10{sup 3}(L/Kg) and sorption capacity of 3,0 g Ta/ Kg EPU. At the optimized conditions analytical curve is linear up to 100{mu}g Ta; sample dilution until 0,3 L makes possible the metal determination with detection (3{sigma}) and quantification (10{sigma}) limits of 3 and 16 ppb, respectively. Ratios of 1:1000 tantalum to niobium, zirconium, uranium, tungsten, tin, iron, aluminium and manganese does not interfere. (author)

  10. The kick-out mass selection technique for ions stored in an Electrostatic Ion Beam Trap

    Energy Technology Data Exchange (ETDEWEB)

    Toker, Y; Altstein, N; Aviv, O; Rappaport, M L; Heber, O; Schwalm, D; Strasser, D; Zajfman, D [Department of Particle Physics, Weizmann Institute of Science, Rehovot, 76100 (Israel)], E-mail: jtoker@weizmann.ac.il

    2009-09-15

    A simple mass selection technique which allows one to clean a keV ion beam of undesirable masses while stored in an Electrostatic Ion Beam Trap (EIBT) is described. The technique is based on the time-of-flight principle and takes advantage of the long storage times and self-bunching that are possible in this type of traps (self bunching being the effect that keeps ions of the same mass bunched in spite of their finite distributions of velocities and trajectories). As the oscillation period is proportional to the square root of the ion mass, bunches containing ions of different masses will separate in space with increasing storage time and can be kicked out by a pulsed deflector mounted inside the trap. A mass selector of this type has been implemented successfully in an EIBT connected to an Even-Lavie supersonic expansion source and is routinely used in ongoing cluster experiments.

  11. State-selected ion-molecule reactions with Coulomb-crystallized molecular ions in traps

    CERN Document Server

    Tong, Xin; Reyes, Juvenal Yosa; Germann, Matthias; Meuwly, Markus; Willitsch, Stefan

    2012-01-01

    State-selected Coulomb-crystallized molecular ions were employed for the first time in ion-molecule reaction studies using the prototypical charge-transfer process $\\mathrm{N_2^++N_2\\rightarrow N_2+N_2^+}$ as an example. By preparing the reactant ions in a well-defined rovibrational state and localizing them in space by sympathetic cooling to millikelvin temperatures in an ion trap, state- and energy-controlled reaction experiments with sensitivities on the level of single ions were performed. The experimental results were interpreted with quasi-classical trajectory simulations on a six-dimensional potential-energy surface which provided detailed insight into translation-to-rotation energy transfer occurring during charge transfer between N$_2$ and N$_2^+$.

  12. Exposure to Fluoride in Smelter Workers in a Primary Aluminum Industry in India

    Directory of Open Access Journals (Sweden)

    A Singh

    2013-04-01

    Full Text Available Background: Fluoride is used increasingly in a variety of industries in India. Emission of fluoride dust and fumes from the smelters of primary aluminum producing industries is dissipated in the work environment and poses occupational health hazards.Objective: To study the prevalence of health complaints and its association with fluoride level in body fluids of smelter workers in a primary aluminum producing industry.Methods: In an aluminum industry, health status of 462 smelter workers, 60 supervisors working in the smelter unit, 62 non-smelter workers (control group 1 and 30 administration staff (control group 2 were assessed between 2007 and 2009. Their health complaints were recorded and categorized into 4 groups: 1 gastro-intestinal complaints; 2 non-skeletal manifestations; 3 skeletal symptoms; and (4 respiratory problems. Fluoride level in body fluids, nails, and drinking water was tested by an ion selective electrode; hemoglobin level was tested using HemoCue.Results: The total complaints reported by study groups were significantly higher than the control groups. Smelter workers had a significantly (pConclusions: Industrial emission of fluoride is not the only important sources of fluoride exposure—consumption of substance with high levels of fluoride is another important route of entry of fluoride into the body. Measurement of hemoglobin provides a reliable indicator for monitoring the health status of employees at risk of fluorosis.

  13. Fluoride content of soft drinks, nectars, juices, juice drinks, concentrates, teas and infusions marketed in Portugal.

    Science.gov (United States)

    Fojo, C; Figueira, M E; Almeida, C M M

    2013-01-01

    A potentiometric method using a fluoride combination ion-selective electrode was validated and used to analyse 183 samples, including soft drinks, juices, nectars, juice drinks, concentrates, teas and infusions marketed in Portugal. The fluoride levels were higher in extract-based soft drinks, juice drinks and juice, with fluoride values of 0.86 ± 0.35, 0.40 ± 0.24 and 0.37 ± 0.11 mg l⁻¹, respectively. The lowest fluoride concentration was found in infusion samples (0.12 ± 0.01 mg l⁻¹), followed by teas and carbonated soft drinks with fluoride concentrations of 0.16 ± 0.12 and 0.18 ± 0.07 mg l⁻¹, respectively. Nectars, concentrates and juice-based drinks had similar fluoride concentrations of 0.33 ± 0.16, 0.29 ± 0.12 and 0.25 ± 0.14 mg l⁻¹, respectively. The fluoride concentrations in all these samples would only contribute intakes below the acceptable daily intake (ADI = 0.05 mg kg⁻¹ body weight day⁻¹), indicating that, individually, these beverages cannot induce fluoride toxicity in the population group of children.

  14. Assessment of total and soluble fluoride content in commercial dentifrices in Davangere: A cross sectional survey

    OpenAIRE

    D J Veeresh; Umesh Wadgave

    2014-01-01

    Introduction: The major reason for decline in dental caries across globe is because of widespread use of fluoride dentifrices. For a fluoride dentifrice to be effective in the control of dental caries, an adequate concentration of the fluoride must be soluble. Objective: To assess soluble fluoride and total fluoride content in selected commercial dentifrices in Davangere. Materials and Methods: The soluble fluoride and total fluoride content in six selected commercial dentifrices in Davangere...

  15. Ion imprinted polymeric nanoparticles for selective separation and sensitive determination of zinc ions in different matrices.

    Science.gov (United States)

    Shamsipur, Mojtaba; Rajabi, Hamid Reza; Pourmortazavi, Seied Mahdi; Roushani, Mahmoud

    2014-01-01

    Preparation of Zn(2+) ion-imprinted polymer (Zn-IIP) nanoparticles is presented in this report. The Zn-IIP nanoparticles are prepared by dissolving stoichiometric amounts of zinc nitrate and selected chelating ligand, 3,5,7,20,40-pentahydroxyflavone, in 15 mL ethanol-acetonitrile (2:1; v/v) mixture as a porogen solvent in the presence of ethylene glycol-dimethacrylate (EGDMA) as cross-linking, methacrylic acid (MAA) as functional monomer, and 2,2-azobisisobutyronitrile (AIBN) as initiator. After polymerization, Cavities in the polymer particles corresponding to the Zn(2+) ions were created by leaching the polymer in HCl aqueous solution. The synthesized IIPs were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence spectroscopy and thermal analysis techniques. Also, the pH range for rebinding of Zn(2+) ion on the IIP and equilibrium binding time were optimized, using flame atomic absorption spectrometry. In selectivity study, it was found that imprinting results increased affinity of the material toward Zn(2+) ion over other competitor metal ions with the same charge and close ionic radius. The prepared IIPs were repeatedly used and regenerated for six times without any significant decrease in polymer binding affinities. Finally, the prepared sorbent was successfully applied to the selective recognition and determination of zinc ion in different real samples.

  16. INTERACTION OF FLUORIDE COMPLEXES DERIVED FROM GLASS-IONOMER CEMENTS WITH HYDROXYAPATITE

    Directory of Open Access Journals (Sweden)

    Lewis S. M.

    2013-09-01

    Full Text Available A study has been undertaken of the interaction of complexed fluoride extracted from glass-ionomer dental cements with synthetic hydroxyapatite powder. Extracts were prepared from two commercial glass-ionomers (Fuji IX and ChemFlex under both neutral and acidic conditions. They were analysed by ICP-OES and by fluoride-ion selective electrode with and without added TISAB to decomplex the fluoride. The pH of the acid extracts was 4, conditions under which fluoride complexes with protons as HF or HF2-, it also complexes with aluminium, which was found to be present in higher amounts in the acid extracts. Fluoride was found to be almost completely complexed in acid extracts, but not in neutral extracts, which contained free fluoride ions. Exposure of these extracts to synthetic hydroxyapatite powder showed that fluoride was taken up rapidly (within 5 minutes, whether or not it was complexed. SEM (EDAX study of recovered hydroxyapatite showed only minute traces of aluminium taken up under all conditions. This showed that aluminium interacts hardly at all with hydroxyapatite, and hence is probably not involved in the remineralisation process.

  17. Nanomolar determination of Pb (II ions by selective templated electrode

    Directory of Open Access Journals (Sweden)

    Mazloum-Ardakani Mohammad

    2012-01-01

    Full Text Available Polypyrrole modified electrode, prepared by electropolymerization of pyrrole in the presence of methyl red as a dopant, was templated with respect to Pb2+ ion and applied for potentiometric and voltammetric detection of this ion. The templating process improved the analytical response characteristics of the electrode, specially their selectivity, with respect to Pb2+ ion. The improvement depends on both the incorporated ligand (dopant and the templating process, with the latter being more vital. The potentiometric response of the electrode was linear within the Pb2+ concentration range of 2.0×10-6 to 5.0×10-2 M with a near-Nernstian slope of 28.6 mV decade-1 and a detection limit of 7.0 ×10-7 M. The electrode was also used for preconcentration differential pulse anodic stripping voltammetry (DPASV and results showed that peak currents for the incorporated lead species were dependent on the metal ion concentration in the range of 1.0×10-8 to 1.0×10-3 M. The detection limit of DPASV method was 3.5 ×10-9 M. The selectivity of the electrode with respect to some transition metal ions was investigated. The modified-templated electrode was used for the successful assay of lead in two standard reference material samples.

  18. Biomimetic ion nanochannels as a highly selective sequential sensor for zinc ions followed by phosphate anions.

    Science.gov (United States)

    Han, Cuiping; Su, Haiyan; Sun, Zhongyue; Wen, Long; Tian, Demei; Xu, Kai; Hu, Junfeng; Wang, Aming; Li, Haibing; Jiang, Lei

    2013-07-08

    A novel biomimetic ion-responsive multi-nanochannel system is constructed by covalently immobilizing a metal-chelating ligand, 2,2'-dipicolylamine (DPA), in polyporous nanochannels prepared in a polymeric membrane. The DPA-modified multi-nanochannels show specific recognition of zinc ions over other common metal ions, and the zinc-ion-chelated nanochannels can be used as secondary sensors for HPO4(2-) anions. The immobilized DPA molecules act as specific-receptor binding sites for zinc ions, which leads to the highly selective zinc-ion response through monitoring of ionic current signatures. The chelated zinc ions can be used as secondary recognition elements for the capture of HPO4(2-) anions, thereby fabricating a sensing nanodevice for HPO4(2-) anions. The success of the DPA immobilization and ion-responsive events is confirmed by measurement of the X-ray photoelectron spectroscopy (XPS), contact angle (CA), and current-voltage (I-V) characteristics of the systems. The proposed nanochannel sensing devices display remarkable specificity, high sensitivity, and wide dynamic range. In addition, control experiments performed in complex matrices suggest that this sensing system has great potential applications in chemical sensing, biotechnology, and many other fields.

  19. Rank-based model selection for multiple ions quantum tomography

    Science.gov (United States)

    Guţă, Mădălin; Kypraios, Theodore; Dryden, Ian

    2012-10-01

    The statistical analysis of measurement data has become a key component of many quantum engineering experiments. As standard full state tomography becomes unfeasible for large dimensional quantum systems, one needs to exploit prior information and the ‘sparsity’ properties of the experimental state in order to reduce the dimensionality of the estimation problem. In this paper we propose model selection as a general principle for finding the simplest, or most parsimonious explanation of the data, by fitting different models and choosing the estimator with the best trade-off between likelihood fit and model complexity. We apply two well established model selection methods—the Akaike information criterion (AIC) and the Bayesian information criterion (BIC)—two models consisting of states of fixed rank and datasets such as are currently produced in multiple ions experiments. We test the performance of AIC and BIC on randomly chosen low rank states of four ions, and study the dependence of the selected rank with the number of measurement repetitions for one ion states. We then apply the methods to real data from a four ions experiment aimed at creating a Smolin state of rank 4. By applying the two methods together with the Pearson χ2 test we conclude that the data can be suitably described with a model whose rank is between 7 and 9. Additionally we find that the mean square error of the maximum likelihood estimator for pure states is close to that of the optimal over all possible measurements.

  20. Fluorination utilizing thermodynamically unstable fluorides and fluoride salts thereof

    Energy Technology Data Exchange (ETDEWEB)

    Bartlett, Neil (Orinda, CA); Whalen, J. Marc (Corning, NY); Chacon, Lisa (Corning, NY)

    2000-12-12

    A method for fluorinating a carbon compound or cationic carbon compound utilizes a fluorination agent selected from thermodynamically unstable nickel fluorides and salts thereof in liquid anhydrous hydrogen fluoride. The desired carbon compound or cationic organic compound to undergo fluorination is selected and reacted with the fluorination agent by contacting the selected organic or cationic organic compound and the chosen fluorination agent in a reaction vessel for a desired reaction time period at room temperature or less.

  1. Salivary-free fluoride ion concentration measured using a flow-injection analysis device and oral environment in 4-6-year-old children.

    Science.gov (United States)

    Iwasaki, Terumi; Uchikawa, Yoshimori; Shirase, Toshiomi

    2016-09-01

    Although fluoride (F) products are widely used for caries prevention, the safest and most effective modes of application, in particular for young children, remain to be elucidated. The limitations associated with the detection of ultra-low F ion concentrations are the major obstacles in accurately assessing the salivary F ion concentrations in children. This study aimed to measure accurate salivary-free F ion concentrations in children using a flow-injection analysis device and highlight the conditions or substances that influence changes in salivary content. Subjects were 4-6-year-old children, and we statistically compared the data involving the number of decayed, missing, or filled surfaces (dmfs), the levels of Mutans streptococci (MS) and Lactobacilli (LB) cariogenic bacteria, and oral hygiene habits. The information on the latter was obtained using a parent/guardian questionnaire. The average free F ion concentration measured was 0.421 ± 0.158 μmol/L (0.008 ± 0.003 ppm), which was considerably lower than that obtained in previous studies using the conventional F electrode method. No significantly different correlations were seen between salivary-free F ion concentrations and dmfs, MS and LB levels. With regard to salivary-free F ion concentrations and oral hygiene habits, only finishing brush of subjects' teeth by guardians showed a significant difference. In summary, the frequency of brushing was shown to correlate with free F ion concentration in saliva of children. Further studies are needed to circumstantially evaluate some other substances in saliva and oral hygiene habits.

  2. Data acquisition system for ion-selective potentiometric sensors

    Science.gov (United States)

    Filipkowski, Andrzej; Ogrodzki, Jan; Opalski, Leszek J.; Rybaniec, Radoslaw; Wieczorek, Piotr Z.

    2009-06-01

    The paper presents an idea and directives on construction of a measurement system for estimation of ions' concentration in water. System presented in paper has been fully designed and manufactured in Warsaw University of Technology in Institute of Electronic Systems. The measurement system works with cheap ion-selective potentiometric sensors. System allows for potentiometric, transient response and voltamperometric measurements. Data fusion method has been implemented in the system to increase the estimation's accuracy. Presented solution contains of many modern electronic elements like 32bit ARM microcontroller, precise operational amplifiers and some hydraulics subsystems essential for chemical measurements.

  3. Nitrate Ion Selective Electrode Based on Ion Imprinted Poly(N-methylpyrrole

    Directory of Open Access Journals (Sweden)

    Ellen M. Bomar

    2017-01-01

    Full Text Available A poly(N-methylpyrrole based ion selective electrode (ISE has been prepared by electro-polymerization of N-methylpyrrole using potassium nitrate as the supporting electrolyte. Electrochemical and chemical variables were used to optimize the potentiometric response of the electrodes and to maximize the selectivity for nitrate over potential interferences. The selectivity, longevity and stability of the ion-imprinted polymer give this electrode advantages over traditional nitrate ISEs. The best prototype electrode exhibits a linear potential response to nitrate ion within the concentration range of 5.0 × 10−6 to 0.1 M nitrate with a near Nernstian slope of −56.3 mV per decade (R2 = 0.9998 and a strong preference for the nitrate ion over other anions. The selectivity coefficients of the electrode were evaluated by the fixed interference method. The use of N-methylpyrrole has advantages over pyrrole in terms of selectivity and pH insensitivity.

  4. Novel N,N'-Diacylhydrazine-Based Colorimetric Receptors for Selective Sensing of Fluoride and Acetate Anions

    Institute of Scientific and Technical Information of China (English)

    SHI, Da-Qing; WANG, Hai-Ying; LI, Xiao-Yue; YANG, Fang; SHI, Jing-Wen; WANG, Xiang-Shan

    2007-01-01

    Three novel and simple N,N'-diacylhydrazine-based colorimetric receptors have been prepared. The binding properties of the receptors to anions such as F-, Cl-, Br-, AcO-, HSO-4 and H2PO-4 in acetonitrile solution were examined by UV-Vis spectroscopy methods, which show high sensitivity and selectivity to F- and AcO- over other anions. The results indicated that a 1:1 stoichiometry complex was formed between the receptors and the anions, while 1H NMR titrations confirmed hydrogen binding interaction between the receptors and the anions.

  5. The Generation of Dehydroalanine Residues in Protonated Polypeptides: Ion/Ion Reactions for Introducing Selective Cleavages

    Science.gov (United States)

    Peng, Zhou; Bu, Jiexun; McLuckey, Scott A.

    2017-05-01

    We examine a gas-phase approach for converting a subset of amino acid residues in polypeptide cations to dehydroalanine (Dha). Subsequent activation of the modified polypeptide ions gives rise to specific cleavage N-terminal to the Dha residue. This process allows for the incorporation of selective cleavages in the structural characterization of polypeptide ions. An ion/ion reaction within the mass spectrometer between a multiply protonated polypeptide and the sulfate radical anion introduces a radical site into the multiply protonated polypeptide reactant. Subsequent collisional activation of the polypeptide radical cation gives rise to radical side chain loss from one of several particular amino acid side chains (e.g., leucine, asparagine, lysine, glutamine, and glutamic acid) to yield a Dha residue. The Dha residues facilitate preferential backbone cleavages to produce signature c- and z-ions, demonstrated with cations derived from melittin, mechano growth factor (MGF), and ubiquitin. The efficiencies for radical side chain loss and for subsequent generation of specific c- and z-ions have been examined as functions of precursor ion charge state and activation conditions using cations of ubiquitin as a model for a small protein. It is noted that these efficiencies are not strongly dependent on ion trap collisional activation conditions but are sensitive to precursor ion charge state. Moderate to low charge states show the greatest overall yields for the specific Dha cleavages, whereas small molecule losses (e.g., water/ammonia) dominate at the lowest charge states and proton catalyzed amide bond cleavages that give rise to b- and y-ions tend to dominate at high charge states.

  6. The Generation of Dehydroalanine Residues in Protonated Polypeptides: Ion/Ion Reactions for Introducing Selective Cleavages

    Science.gov (United States)

    Peng, Zhou; Bu, Jiexun; McLuckey, Scott A.

    2017-09-01

    We examine a gas-phase approach for converting a subset of amino acid residues in polypeptide cations to dehydroalanine (Dha). Subsequent activation of the modified polypeptide ions gives rise to specific cleavage N-terminal to the Dha residue. This process allows for the incorporation of selective cleavages in the structural characterization of polypeptide ions. An ion/ion reaction within the mass spectrometer between a multiply protonated polypeptide and the sulfate radical anion introduces a radical site into the multiply protonated polypeptide reactant. Subsequent collisional activation of the polypeptide radical cation gives rise to radical side chain loss from one of several particular amino acid side chains (e.g., leucine, asparagine, lysine, glutamine, and glutamic acid) to yield a Dha residue. The Dha residues facilitate preferential backbone cleavages to produce signature c- and z-ions, demonstrated with cations derived from melittin, mechano growth factor (MGF), and ubiquitin. The efficiencies for radical side chain loss and for subsequent generation of specific c- and z-ions have been examined as functions of precursor ion charge state and activation conditions using cations of ubiquitin as a model for a small protein. It is noted that these efficiencies are not strongly dependent on ion trap collisional activation conditions but are sensitive to precursor ion charge state. Moderate to low charge states show the greatest overall yields for the specific Dha cleavages, whereas small molecule losses (e.g., water/ammonia) dominate at the lowest charge states and proton catalyzed amide bond cleavages that give rise to b- and y-ions tend to dominate at high charge states. [Figure not available: see fulltext.

  7. Rapid detection of fluoride in potable water using a novel fluorogenic compound 7-O-tert-butyldiphenylsilyl-4-methylcoumarin

    Directory of Open Access Journals (Sweden)

    Ravi Chavali

    2015-12-01

    Full Text Available In the present work, we have synthesized a new water soluble colorless chemical compound 7-O-tert-butyldiphenylsilyl-4-methylcoumarin (TBDPSC that releases fluorescent molecules imparting blue fluorescence to the solution, upon interaction with fluoride ions in water. The blue fluorescence can be visualized using simple hand held ultraviolet (UV lamps. TBDPSC has excellent sensitivity and selectivity towards fluoride and our results indicate that fluoride concentrations as low as 0.2 mg/L can be accurately detected within a few seconds. Fluoride testing with TBDPSC is simple and rapid compared to the conventional methodologies without the requirement of trained personnel. Hence, the present fluoride detection method can be easily field deployable and particularly useful for monitoring water quality in limited resource communities.

  8. A comparative study of fluoride ingestion levels, serum thyroid hormone & TSH level derangements, dental fluorosis status among school children from endemic and non-endemic fluorosis areas.

    Science.gov (United States)

    Singh, Navneet; Verma, Kanika Gupta; Verma, Pradhuman; Sidhu, Gagandeep Kaur; Sachdeva, Suresh

    2014-01-03

    The study was undertaken to determine serum/urinary fluoride status and comparison of free T4, free T3 and thyroid stimulating hormone levels of 8 to 15 years old children with and without dental fluorosis living in an endemic and non-endemic fluorosis area. A sample group of 60 male and female school children, with or without dental fluorosis, consuming fluoride-contaminated water in endemic fluoride area of Udaipur district, Rajasthan were selected through a school dental fluorosis survey. The sample of 10 children of same age and socio-economic status residing in non endemic areas who did not have dental fluorosis form controls. Fluoride determination in drinking water, urine and blood was done with Ion 85 Ion Analyzer Radiometer with Hall et al. method. The thyroid gland functional test was done by Immonu Chemiluminiscence Micropartical Assay with Bayer Centaur Autoanalyzer. The significantly altered FT3, FT4 and TSH hormones level in both group1A and 1B school children were noted. The serum and urine fluoride levels were found to be increased in both the groups. A significant relationship of water fluoride to urine and serum fluoride concentration was seen. The serum fluoride concentration also had significant relationship with thyroid hormone (FT3/FT4) and TSH concentrations. The testing of drinking water and body fluids for fluoride content, along with FT3, FT4, and TSH in children with dental fluorosis is desirable for recognizing underlying thyroid derangements and its impact on fluorosis.

  9. Structure and electrochemical properties of composite polymer electrolyte based on poly vinylidene fluoride-hexafluoropropylene/titania-poly(methyl methacrylate) for lithium-ion batteries

    Science.gov (United States)

    Cao, Jiang; Wang, Li; Fang, Mou; He, Xiangming; Li, Jianjun; Gao, Jian; Deng, Lingfeng; Wang, Jianlong; Chen, Hong

    2014-01-01

    Titania-poly(methyl methacrylate) (PMMA) organic-inorganic hybrid material is synthesized via in situ polymerization. The hybrid material is employed to prepare poly vinylidene fluoride-hexafluoropropylene (PVdF-HFP) composite polymer electrolyte. The effect of the hybrid material is investigated by SEM, TG-DSC, AC impedance and charge/discharge cycling tests. The results demonstrate that the inorganic-organic hybrid material as additive increases the porosity, pore size and electrolyte uptake of the PVdF-HFP composite polymer electrolyte membrane, so that the ionic conductivity of the composite polymer electrolyte membrane is improved. The performance enhancement of the composite polymer electrolyte is confirmed by an electrochemical test using LiCoO2/Li cells in the voltage range of 2.75-4.4 V. This study shows that titania-PMMA hybrid material is a promising additive for PVDF-HFP composite polymer electrolyte for Li-ion batteries.

  10. In situ ceramic fillers of electrospun thermoplastic polyurethane/poly(vinylidene fluoride) based gel polymer electrolytes for Li-ion batteries

    Science.gov (United States)

    Wu, Na; Cao, Qi; Wang, Xianyou; Li, Sheng; Li, Xiaoyun; Deng, Huayang

    Gel polymer electrolyte films based on thermoplastic polyurethane (TPU)/poly(vinylidene fluoride) (PVdF) with and without in situ ceramic fillers (SiO 2 and TiO 2) are prepared by electrospinning 9 wt% polymer solution at room temperature. The electrospun TPU-PVdF blending membrane with 3% in situ TiO 2 shows a highest ionic conductivity of 4.8 × 10 -3 S cm -1 with electrochemical stability up to 5.4 V versus Li +/Li at room temperature and has a high tensile strength (8.7 ± 0.3 MPa) and % elongation at break (110.3 ± 0.2). With the superior electrochemical and mechanical performance, it is very suitable for application in polymer lithium ion batteries.

  11. Effect of silica nanoparticles/poly(vinylidene fluoride-hexafluoropropylene) coated layers on the performance of polypropylene separator for lithium-ion batteries

    Institute of Scientific and Technical Information of China (English)

    Hongyu Liu; Zehui Dai; Jun Xu; Baohua Guo; Xiangming He

    2014-01-01

    In an effort to reduce thermal shrinkage and improve electrochemical performance of porous polypropylene (PP) separators for lithium-ion batteries, a new composite separator is developed by introducing ceramic coated layers on both sides of PP separator through a dip-coating process. The coated layers are comprised of heat-resistant and hydrophilic silica nanoparticles and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) binders. Highly porous honeycomb structure is formed and the thickness of the layer is only about 700 nm. In comparison to the pristine PP separator, the composite separator shows significant reduction in thermal shrinkage and improvement in liquid electrolyte uptake and ionic conduction, which play an important role in improving cell performance such as discharge capacity, C-rate capability, cycle performance and coulombic efficiency.

  12. Quantum Model for the Selectivity Filter in K$^{+}$ Ion Channel

    CERN Document Server

    Cifuentes, A A

    2013-01-01

    In this work, we present a quantum transport model for the selectivity filter in the KcsA potassium ion channel. This model is fully consistent with the fact that two conduction pathways are involved in the translocation of ions thorough the filter, and we show that the presence of a second path may actually bring advantages for the filter as a result of quantum interference. To highlight interferences and resonances in the model, we consider the selectivity filter to be driven by a controlled time-dependent external field which changes the free energy scenario and consequently the conduction of the ions. In particular, we demonstrate that the two-pathway conduction mechanism is more advantageous for the filter when dephasing in the transient configurations is lower than in the main configurations. As a matter of fact, K$^+$ ions in the main configurations are highly coordinated by oxygen atoms of the filter backbone and this increases noise. Moreover, we also show that, for a wide range of driving frequencie...

  13. Ion-selective carbon-paste electrodes for halides and silver(I) ions

    NARCIS (Netherlands)

    Mesaric, S.; Dahmen, E.A.M.F.

    1973-01-01

    The behaviour of a simple type of ion-selective electrode for halogens and silver has been studied. The electrode consists of a plastic body filled with carbon paste, the surface of which can be easily renewed. The paste composition is based on carbon-nujol (5:1, w/v) or carbon-paraffin wax (3:1,w/w

  14. Selective activation of mechanosensitive ion channels using magnetic particles.

    Science.gov (United States)

    Hughes, Steven; McBain, Stuart; Dobson, Jon; El Haj, Alicia J

    2008-08-01

    This study reports the preliminary development of a novel magnetic particle-based technique that permits the application of highly localized mechanical forces directly to specific regions of an ion-channel structure. We demonstrate that this approach can be used to directly and selectively activate a mechanosensitive ion channel of interest, namely TREK-1. It is shown that manipulation of particles targeted against the extended extracellular loop region of TREK-1 leads to changes in whole-cell currents consistent with changes in TREK-1 activity. Responses were absent when particles were coated with RGD (Arg-Gly-Asp) peptide or when magnetic fields were applied in the absence of magnetic particles. It is concluded that changes in whole-cell current are the result of direct force application to the extracellular loop region of TREK-1 and thus these results implicate this region of the channel structure in mechano-gating. It is hypothesized that the extended loop region of TREK-1 may act as a tension spring that acts to regulate sensitivity to mechanical forces, in a nature similar to that described for MscL. The development of a technique that permits the direct manipulation of mechanosensitive ion channels in real time without the need for pharmacological drugs has huge potential benefits not only for basic biological research of ion-channel gating mechanisms, but also potentially as a tool for the treatment of human diseases caused by ion-channel dysfunction.

  15. Selective deuterium ion acceleration using the Vulcan petawatt laser

    Energy Technology Data Exchange (ETDEWEB)

    Krygier, A. G. [Laboratoire pour l' Utilisation des Lasers Intenses, École Polytechnique, 91128 Palasiseau (France); Physics Department, The Ohio State University, Columbus, Ohio 43210 (United States); Morrison, J. T. [Propulsion Systems Directorate, Air Force Research Lab, Wright Patterson Air Force Base, Ohio 45433 (United States); Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.; Alejo, A.; Green, A.; Jung, D. [Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Clarke, R.; Notley, M. [Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Fuchs, J.; Vassura, L. [Laboratoire pour l' Utilisation des Lasers Intenses, École Polytechnique, 91128 Palasiseau (France); Kleinschmidt, A.; Roth, M. [Institut für Kernphysik, Technische Universität Darmstadt, Schloßgartenstrasse 9, D-64289 Darmstadt (Germany); Najmudin, Z.; Nakamura, H. [The John Adams Institute, Blackett Laboratory, Department of Physics, Imperial College, London SW7 2AZ (United Kingdom); Norreys, P. [Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom); Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Oliver, M. [Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Zepf, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Helmholtz Institute Jena, D-07743 Jena (Germany); Borghesi, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Institute of Physics of the ASCR, ELI-Beamlines Project, Na Slovance 2, 18221 Prague (Czech Republic); Freeman, R. R. [Physics Department, The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-05-15

    We report on the successful demonstration of selective acceleration of deuterium ions by target-normal sheath acceleration (TNSA) with a high-energy petawatt laser. TNSA typically produces a multi-species ion beam that originates from the intrinsic hydrocarbon and water vapor contaminants on the target surface. Using the method first developed by Morrison et al. [Phys. Plasmas 19, 030707 (2012)], an ion beam with >99% deuterium ions and peak energy 14 MeV/nucleon is produced with a 200 J, 700 fs, >10{sup 20}W/cm{sup 2} laser pulse by cryogenically freezing heavy water (D{sub 2}O) vapor onto the rear surface of the target prior to the shot. Within the range of our detectors (0°–8.5°), we find laser-to-deuterium-ion energy conversion efficiency of 4.3% above 0.7 MeV/nucleon while a conservative estimate of the total beam gives a conversion efficiency of 9.4%.

  16. Comparison of the Amount of Fluoride Release from Nanofilled Resin Modified Glass Ionomer Conventional and Resin Modified Glass Ionomer Cements

    Directory of Open Access Journals (Sweden)

    Sumitha Upadhyay

    2013-01-01

    Full Text Available Objective: To investigate and compare the amount of fluoride release of conventional, resin modified and nanofilled resin modified glass ionomer cements.Materials and Methods: Tablets of glass-ionomer cements were immersed in deionized water and incubated at 37◦C. After 1, 2, 7, 15 and 30 days, fluoride ion was measured under normal atmospheric conditions by fluoride ion selective electrode. Buffer (TISAB II was used to decomplex the fluoride ion and to provide a constant background ionic strength and to maintain the pH of water between 5.0 and 5.5 as the fluoride electrode is sensitive to changes in pH. Statistical evaluation was carried out by one way ANOVA (Analysis of Variance using SPSS 11.0. The significance level was set at p< 0.05.Results: The release of fluoride was highest on day 1 and there was a sudden fall on day 2 in all three groups. Initially fluoride release from conven-tional glass-ionomer cement was highest compared to the other two glass-ionomer cements, but the amount drastically reduced over the period. Although the amount of fluoride release was less than both the resin modified and nanofilled resin modified glass-ionomer cement, the release was sustained consistently for 30 daysConclusion: The cumulative fluoride release of nanofilled resin modified glass ionomer cement was very less compared to the conventional and resin modified glass ionomer cements and Nanofilled resin modified glass ionomer cement released less but steady fluoride as compared to other resin modified glass ionomer cements.

  17. Renal fluoride excretion in children following topical application of fluoride varnish.

    Science.gov (United States)

    García-Hoyos, F; Barbería, E; García-Camba, P; Varela, M

    2012-12-01

    To demonstrate that the application of dental fluoride varnishes in children increases urinary fluoride excretion. From a randomly assembled group of 42 children aged between 5 and 8 years, residing in a community with non-fluoridated water, spot urinary samples were taken before the topical application of dental fluoride varnish and 2 hours afterwards. In an age-matched control group of 16 children from the same community, who received no treatment, samples were taken the same way. The urinary excretion of fluoride was analysed by determining fluoride ion (F-) level and fluoride/creatinine (F/Cr) ratio in the urine. In the study group, the average pre- and post-treatment F/Cr ratios were 0.42 and 1.38 mg/g, respectively (p fluoride varnish leads to a significant increase in urine F-, which is attributable to the application of the product.

  18. Fluoride in drinking water, brick tea infusion and human urine in two counties in Inner Mongolia, China.

    Science.gov (United States)

    Li, Hai-rong; Liu, Qing-bin; Wang, Wu-yi; Yang, Lin-sheng; Li, Yong-hua; Feng, Fu-jian; Zhao, Xiao-yu; Hou, Kun; Wang, Ge

    2009-08-15

    The objective of this study was to detect the fluoride level in the drinking water and the urine of habitants aged 16-55 years living in Inner Mongolia China. Furthermore, fluoride concentration of the brick tea infusion samples which were drunk by Mongolia herdsmen in everyday life living in SumuErga village of Ejin Horo Banner, Inner Mongolia China was also determined. A total of 117 participants (61 female and 56 male) were recruited from two counties for a cross-sectional study on health effects of chronic fluoride exposure from drinking water and drinking brick tea infusion. The fluoride concentration in drinking water, urine and brick tea infusion samples were determined using fluoride ion selective electrode method obtained from the Ministry of Health of the People's Republic of China. The average fluoride concentration in drinking water samples was 0.32+/-0.01 mg/L at AretengXire town of Ejin Horo Banner, 0.70+/-0.19 mg/L at SumuErga village of Ejin Horo Banner, and 2.68+/-1.15 mg/L at ZhalaiNuoer district of Manzhouli city. The average fluoride concentration in brick tea infusion samples which collected from Mongolia herdsmen at SumuErga village of Ejin Horo Banner was 1.81+/-1.09 mg/L. The average urinary fluoride concentration at AretengXire town of Ejin Horo Banner was 0.59+/-0.48 mg/L, at SumuErga village of Ejin Horo Banner was 1.45+/-0.93 mg/L and at ZhalaiNuoer district of Manzhouli city was 3.06+/-1.53 mg/L. The higher fluoride levels in the urine of participants may be associated to higher fluoride in drinking water at ZhalaiNuoer of Manzhouli city. However, drinking brick tea infusions with higher fluoride may be the cause of the higher fluoride contents in the Mongolia herdsmen's urine.

  19. Structural foundations of optogenetics: Determinants of channelrhodopsin ion selectivity.

    Science.gov (United States)

    Berndt, Andre; Lee, Soo Yeun; Wietek, Jonas; Ramakrishnan, Charu; Steinberg, Elizabeth E; Rashid, Asim J; Kim, Hoseok; Park, Sungmo; Santoro, Adam; Frankland, Paul W; Iyer, Shrivats M; Pak, Sally; Ährlund-Richter, Sofie; Delp, Scott L; Malenka, Robert C; Josselyn, Sheena A; Carlén, Marie; Hegemann, Peter; Deisseroth, Karl

    2016-01-26

    The structure-guided design of chloride-conducting channelrhodopsins has illuminated mechanisms underlying ion selectivity of this remarkable family of light-activated ion channels. The first generation of chloride-conducting channelrhodopsins, guided in part by development of a structure-informed electrostatic model for pore selectivity, included both the introduction of amino acids with positively charged side chains into the ion conduction pathway and the removal of residues hypothesized to support negatively charged binding sites for cations. Engineered channels indeed became chloride selective, reversing near -65 mV and enabling a new kind of optogenetic inhibition; however, these first-generation chloride-conducting channels displayed small photocurrents and were not tested for optogenetic inhibition of behavior. Here we report the validation and further development of the channelrhodopsin pore model via crystal structure-guided engineering of next-generation light-activated chloride channels (iC++) and a bistable variant (SwiChR++) with net photocurrents increased more than 15-fold under physiological conditions, reversal potential further decreased by another ∼ 15 mV, inhibition of spiking faithfully tracking chloride gradients and intrinsic cell properties, strong expression in vivo, and the initial microbial opsin channel-inhibitor-based control of freely moving behavior. We further show that inhibition by light-gated chloride channels is mediated mainly by shunting effects, which exert optogenetic control much more efficiently than the hyperpolarization induced by light-activated chloride pumps. The design and functional features of these next-generation chloride-conducting channelrhodopsins provide both chronic and acute timescale tools for reversible optogenetic inhibition, confirm fundamental predictions of the ion selectivity model, and further elucidate electrostatic and steric structure-function relationships of the light-gated pore.

  20. Distinct regions that control ion selectivity and calcium-dependent activation in the bestrophin ion channel.

    Science.gov (United States)

    Vaisey, George; Miller, Alexandria N; Long, Stephen B

    2016-11-22

    Cytoplasmic calcium (Ca(2+)) activates the bestrophin anion channel, allowing chloride ions to flow down their electrochemical gradient. Mutations in bestrophin 1 (BEST1) cause macular degenerative disorders. Previously, we determined an X-ray structure of chicken BEST1 that revealed the architecture of the channel. Here, we present electrophysiological studies of purified wild-type and mutant BEST1 channels and an X-ray structure of a Ca(2+)-independent mutant. From these experiments, we identify regions of BEST1 responsible for Ca(2+) activation and ion selectivity. A "Ca(2+) clasp" within the channel's intracellular region acts as a sensor of cytoplasmic Ca(2+). Alanine substitutions within a hydrophobic "neck" of the pore, which widen it, cause the channel to be constitutively active, irrespective of Ca(2+). We conclude that the primary function of the neck is as a "gate" that controls chloride permeation in a Ca(2+)-dependent manner. In contrast to what others have proposed, we find that the neck is not a major contributor to the channel's ion selectivity. We find that mutation of a cytosolic "aperture" of the pore does not perturb the Ca(2+) dependence of the channel or its preference for anions over cations, but its mutation dramatically alters relative permeabilities among anions. The data suggest that the aperture functions as a size-selective filter that permits the passage of small entities such as partially dehydrated chloride ions while excluding larger molecules such as amino acids. Thus, unlike ion channels that have a single "selectivity filter," in bestrophin, distinct regions of the pore govern anion-vs.-cation selectivity and the relative permeabilities among anions.

  1. Evaluation of an ion-selective electrolyte analyzer: Microlyte 6.

    Science.gov (United States)

    Markova, V; Sirakova, I; Tsvetkova, T; Nikolov, R

    1997-01-01

    Microlyte 6 (Kone, Finland) is an ion-selective analyzer designed to measure simultaneously the concentration of six important electrolyte parameters--potassium, sodium, chloride, ionized calcium, ionized magnesium and pH in whole blood, serum and plasma. Two values are obtained in analyzing the ionized fractions of magnesium and calcium--one at the actual pH and another at a recalculated measurement for pH = 7.4. Direct determination of ionized calcium and ionized magnesium simultaneously with that of the other electrolytes is of great clinical significance. It is only recently that ion-selective analysis of ionized magnesium has been proposed. The analytical reliability of the results and the operational characteristics of the Microlyte 6 ion-selective analyzer were evaluated for approximately one year. The coefficient of variation of the results in the reference and pathological range was 0.49%-2.23%, and 0.68%-4.42% for the within-run and between-run series, respectively. The inaccuracy of the results expressed by d% was from -4.23% to +4.06%. The comparative evaluation of the results for potassium, sodium, chloride, and ionized calcium between Microlyte-6 and the clinical chemistry analyzer Dynamic (Kone) showed a high correlation (correlation coefficient in the range 0.9868-0.9970). The correlation between the results for the ionized fraction and those obtained for total magnesium was consistent with that generally given in the literature.

  2. Environmental fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Marier, J.R.; Rose, D.

    1971-01-01

    Modern-day man is probably exposed to more environmental fluoride than was heretofore suspected, and consideration must be given to the total ingestion from various sources as well as the types of fluoride present in air, foods, beverages, and other commodities. An effort should also be made to study the symptomology of chronic fluorine intoxication, especially the early non-skeletal manifestations of arthritic-like symptoms that may be complicated by metabolic and/or nutritional inadequacies. Finally, it must be emphasized again that dental fluorosis (i.e. mottling) will only be seen in subjects who have been exposed to fluoride during the time when the enamel of the permanent teeth is being formed, and its absence cannot be assumed to indicate freedom from other fluoride-induced effects including effects of organofluorides and their metabolites. 168 references.

  3. Enhanced Wettability and Thermal Stability of a Novel Polyethylene Terephthalate-Based Poly(Vinylidene Fluoride) Nanofiber Hybrid Membrane for the Separator of Lithium-Ion Batteries.

    Science.gov (United States)

    Zhu, Chunhong; Nagaishi, Tomoki; Shi, Jian; Lee, Hoik; Wong, Pok Yin; Sui, Jianhua; Hyodo, Kenji; Kim, Ick Soo

    2017-08-09

    In this study, a novel membrane for the separator in a lithium-ion (Li-ion) battery was proposed via a mechanically pressed process with a poly(vinylidene fluoride) (PVDF) nanofiber subject and polyethylene terephthalate (PET) microfiber support. Important physical properties, such as surface morphology, wettability, and heat stability were considered for the PET-reinforced PVDF nanofiber (PRPN) hybrid separator. Images of scanning electron microscopy (SEM) showed that the PRPN hybrid separator had a homogeneous pore size and high porosity. It can wet out in battery electrolytes completely and quickly, satisfying wettability requirements. Moreover, the electrolyte uptake was higher than that of dry-laid and wet-laid nonwovens. For heat stability, no shrink occurred even when the heating temperature reached 135 °C, demonstrating thermal and dimensional stability. Moreover, differential scanning calorimetry (DSC) showed that the PRPN hybrid separator possessed a shutdown temperature of 131 °C, which is the same as conventional separators. Also, the meltdown temperature reached 252 °C, which is higher than the shutdown temperature, and thus can protect against internal cell shorts. The proposed PRPN hybrid separator is a strong candidate material for utilization in Li-ion batteries.

  4. Determination of Nd3+ Ions in Solution Samples by a Coated Wire Ion-Selective Sensor

    Directory of Open Access Journals (Sweden)

    Hassan Ali Zamani

    2012-01-01

    Full Text Available A new coated wire electrode (CWE using 5-(methylsulfanyl-3-phenyl-1H-1,2,4-triazole (MPT as an ionophore has been developed as a neodymium ion-selective sensor. The sensor exhibits Nernstian response for the Nd3+ ions in the concentration range of 1.0×10−6-1.0×10−2 M with detection limit of 3.7×10−7 M. It displays a Nernstian slope of 20.2±0.2 mV/decade in the pH range of 2.7–8.1. The proposed sensor also exhibits a fast response time of ∼5 s. The sensor revealed high selectivity with respect to all common alkali, alkaline earth, transition and heavy metal ions, including members of the lanthanide family other than Nd3+. The electrode was used as an indicator electrode in the potentiometric titration of Nd(III ions with EDTA. The electrode was also employed for the determination of the Nd3+ ions concentration in water solution samples.

  5. Non-equilibrium dynamics contribute to ion selectivity in the KcsA channel.

    Directory of Open Access Journals (Sweden)

    Van Ngo

    Full Text Available The ability of biological ion channels to conduct selected ions across cell membranes is critical for the survival of both animal and bacterial cells. Numerous investigations of ion selectivity have been conducted over more than 50 years, yet the mechanisms whereby the channels select certain ions and reject others are not well understood. Here we report a new application of Jarzynski's Equality to investigate the mechanism of ion selectivity using non-equilibrium molecular dynamics simulations of Na(+ and K(+ ions moving through the KcsA channel. The simulations show that the selectivity filter of KcsA adapts and responds to the presence of the ions with structural rearrangements that are different for Na(+ and K(+. These structural rearrangements facilitate entry of K(+ ions into the selectivity filter and permeation through the channel, and rejection of Na(+ ions. A mechanistic model of ion selectivity by this channel based on the results of the simulations relates the structural rearrangement of the selectivity filter to the differential dehydration of ions and multiple-ion occupancy and describes a mechanism to efficiently select and conduct K(+. Estimates of the K(+/Na(+ selectivity ratio and steady state ion conductance for KcsA from the simulations are in good quantitative agreement with experimental measurements. This model also accurately describes experimental observations of channel block by cytoplasmic Na(+ ions, the "punch through" relief of channel block by cytoplasmic positive voltages, and is consistent with the knock-on mechanism of ion permeation.

  6. The selective separation of Cs and Sr ion on the inorganic ion-exchanger zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hun Hwee; Min, Byeog Heon [Hoseo University, Taegu (Korea)

    1998-04-01

    This study shows the selective separation of Cs and Sr ion on the inorganic ion-exchanger zeolites such as clinoptilolite, Y-type CBV760, CBV780 and A-type 3A. The selective separation of Cs and Sr on these zeolites was examined using batch and continuous column experiments. For the selective separation of Cs and Sr from a synthetic wastewater, adsorption rate of Cs increased in the order, clinoptilolite> 3A>> CBV760> CBV780, adsorption rate of Sr increased in the other, 3A>> clinoptilolite> CBV760> CBV780. For the clinoptilolite, the adsorption rate of Cs reached about 96 {approx} 98% within 3h. The adsorption rate of Sr on 3A reached about 99% within 3h. (author). 40 refs., 27 figs., 4 tabs.

  7. Ion-selective electrodes using carbon nanotubes as ion-to-electron transducers.

    Science.gov (United States)

    Crespo, Gastón A; Macho, Santiago; Rius, F Xavier

    2008-02-15

    This study developed a new type of all-solid-state ion-selective electrode based on a transducing layer of a network of single-walled carbon nanotubes. The extraordinary capacity of carbon nanotubes to promote electron transfer between heterogeneous phases made the presence of electroactive polymers or any other ion-to-electron-transfer promoter unnecessary. The new transducer layer was characterized by environmental scanning electron microscopy and electrochemical impedance spectroscopy. The stability of the electrical potential of the new solid-contact electrode was examined by performing current-reversal chronopotentiometry, and the influence of the interfacial water film was assessed by the potentiometric water layer test. The performance of the new electrode was evaluated by determining K+ with an ion-selective membrane that contained the well-known valinomycin ion carrier. The new electrode had a Nernstian slope (58.4 mV/decade), dynamic ranges of four logarithmic units, and selectivities and limits of detection comparable to other solid-contact electrodes. The short response time (less than 10 s for activities higher than 10(-5.5) M) and the stability of the signal over several days makes these new electrodes very promising candidates for attaining true miniaturization.

  8. Other Fluoride Products

    Science.gov (United States)

    ... What's this? Submit What's this? Submit Button Other Fluoride Products Recommend on Facebook Tweet Share Compartir On ... August 17, 2001;50(RR-14):1–42. Fluoride Products Fluoride Toothpaste Form Concentrations of fluoride in ...

  9. Bottled Water and Fluoride

    Science.gov (United States)

    ... bottled water and fluoride. Does bottled water contain fluoride? Bottled water products may contain fluoride, depending on ... How can I find out the level of fluoride in bottled water? The FDA does not require ...

  10. Other Fluoride Products

    Science.gov (United States)

    ... Water Fluoridation Journal Articles for Community Water Fluoridation Other Fluoride Products Recommend on Facebook Tweet Share Compartir ... Use the information listed below to compare the other fluoride products that may lower the risk for ...

  11. Comparison of salivary fluoride levels following use of dentifrices containing different concentrations of fluoride

    Directory of Open Access Journals (Sweden)

    Nagpal D

    2007-03-01

    Full Text Available Many industrialized countries have reported a decline in caries prevalence over the past few decades. These reductions have been related to the regular use of fluoride dentifrices. Fluoride dentifrices are the most cost-effective and efficient means of caries prevention. However, there have been concerns regarding the risk of fluorosis in children due to the ingestion of dentifrices. This has led to the use of dentifrices with low concentration of fluoride. Salivary fluoride levels after tooth-brushing have been shown to be related to the anticaries efficacy of fluoride dentifrices. The present study was designed to evaluate the effect of the concentration of fluoride in the dentifrice, on the salivary fluoride level in children. Twenty children in the age group of five to six years were randomly selected and divided into two groups using, either 500ppm or 1000ppm fluoride dentifrice (sodium monofluorophosphate. Salivary fluoride levels at 0, 15, 30, 45, 60, minutes after brushing were estimated. The data collected was statistically evaluated using the unpaired t-test. The results showed that salivary fluoride levels following use of 500ppm fluoride dentifrice were significantly lower than 1000ppm fluoride dentifrice. The low salivary fluoride levels may thereby reduce the anticaries efficacy. Hence, the pros and cons of recommending a low fluoride concentration dentifrice must be judiciously considered.

  12. The structure and regulation of magnesium selective ion channels.

    Science.gov (United States)

    Payandeh, Jian; Pfoh, Roland; Pai, Emil F

    2013-11-01

    The magnesium ion (Mg(2+)) is the most abundant divalent cation within cells. In man, Mg(2+)-deficiency is associated with diseases affecting the heart, muscle, bone, immune, and nervous systems. Despite its impact on human health, little is known about the molecular mechanisms that regulate magnesium transport and storage. Complete structural information on eukaryotic Mg(2+)-transport proteins is currently lacking due to associated technical challenges. The prokaryotic MgtE and CorA magnesium transport systems have recently succumbed to structure determination by X-ray crystallography, providing first views of these ubiquitous and essential Mg(2+)-channels. MgtE and CorA are unique among known membrane protein structures, each revealing a novel protein fold containing distinct arrangements of ten transmembrane-spanning α-helices. Structural and functional analyses have established that Mg(2+)-selectivity in MgtE and CorA occurs through distinct mechanisms. Conserved acidic side-chains appear to form the selectivity filter in MgtE, whereas conserved asparagines coordinate hydrated Mg(2+)-ions within the selectivity filter of CorA. Common structural themes have also emerged whereby MgtE and CorA sense and respond to physiologically relevant, intracellular Mg(2+)-levels through dedicated regulatory domains. Within these domains, multiple primary and secondary Mg(2+)-binding sites serve to staple these ion channels into their respective closed conformations, implying that Mg(2+)-transport is well guarded and very tightly regulated. The MgtE and CorA proteins represent valuable structural templates to better understand the related eukaryotic SLC41 and Mrs2-Alr1 magnesium channels. Herein, we review the structure, function and regulation of MgtE and CorA and consider these unique proteins within the expanding universe of ion channel and transporter structural biology.

  13. Assessment of Fluoride Levels in Different Brands of Black and Green Tea Consumed in Iran

    Directory of Open Access Journals (Sweden)

    F. Mojarad

    2013-01-01

    Full Text Available Introduction & Objective: Tea is one of the most commonly consumed drinks in the world. Tea is recognized as a source of fluoride whose intake may increase the risk of developing dental fluorosis, particularly if other sources of fluoride augment the intake. Since the amount of fluoride in different types of tea consumed in our country is unknown, the purpose of this study was to evaluate the fluoride level of 22 commercial brands of tea popular in Iran. Materials & Methods: This descriptive study was conducted to assess the fluoride content of black tea (10 brands, bagged black tea (9 brands, and green tea (3 brands. 2 g from three samples of each tea brand taken out randomly were added to 200 ml deionized water and boiled for 10 minutes. After the infusion temperature coming down to the room temperature, the infusion was filtered and its volume made up to 200 ml by adding deionized water. The fluoride levels were measured using ion-selective electrode, and reported as mg/lit. Data were analyzed by ANOVA and Tukey test. Results: The Fluoride content was found 1.51 mg/lit in black tea bag, 1.038 mg/lit in green tea and 0.869±0.360 mg/lit in black tea sticks. (P<0.05, However, there was no statistically sig-nificant difference of fluoride concentration between green tea and black tea sticks(P= 0.52. Conclusion: This study showed that fluoride content of some tea brands were so high that drinking a few cups daily may increase the risk of developing dental fluorosis. Therefore, their consumption must be limited particularly in children, and in all inhabitants of regions with high fluoride levels in water supply.(Sci J Hamadan Univ Med Sci 2013; 19 (4:36-42

  14. Mapping of second-nearest-neighbor fluoride ions of orthorhombic Gd 3+-Ag + complexes in CaF 2

    Science.gov (United States)

    Nakata, R.; Den Hartog, H. W.

    The ENDOR technique is applied to determine the positions of 24 second-nearest-neighbor F - ions around an orthorhombic Gd 3+-Ag + complex in CaF 2 crystals. Experimental ENDOR data of the second-nearest-neighbor F - ions are analyzed by using the usual spin Hamiltonian and a least-squares fitting method. The best fits of the experimental results give superhyperfine (shf) constants and the F - directions ( K, L, M) with respect to the Gd 3+ ion, from which the distance between the second-nearest-neighbor F - ion and the Gd 3+ ion is determined by assuming that the hyperfine interaction is due to the classical dipole-dipole interaction. The displacements of the F - ions are estimated and compared with the theoretical values calculated by Bijvank and den Hartog on the basis of a polarizable point charge model.

  15. Fluoride Content of Bottled Drinking Water Available in North West of Iran

    Directory of Open Access Journals (Sweden)

    Reza Fouladi Fard

    2015-06-01

    Full Text Available Background: Consumption of bottled waters has received popularity and more acceptances. Fluoride is necessary for human life. But high levels of fluoride can cause some problems for human health such as Fluorosis and teeth and bones problems. The aim of this study is measure the fluoride content in bottled waters consumed in North West of Iran and comparison with the amount listed on their labels and with the drinking water standards. Methods: In this study, 10 brands of bottled water were sampled from markets over the two seasons randomly. Samples were analyzed for fluoride using Ion Chromatography (IC method. Results: Results showed that fluoride concentration in different brands had a significant difference (P <0.05. The concentration of fluoride in samples ranged between 0.04 and 0.32 mg/L. Among analyzed selected brands four brands were observed significant differences with the measured values. Conclusion:  Totally the measured values didn’t match with the values declared on the labels (Reliability coefficient <0. It was revealed that fluoride concentration in all brands was less than the lower range of Iranian national standard (0.7-1.2 mg/lit.

  16. Selection of RIB targets using ion implantation at the Holifield Radioactive Ion Beam Facility

    Science.gov (United States)

    Alton, G. D.; Dellwo, J.

    1996-02-01

    Among several major challenges posed by generating and accelerating adequate intensities of RIBs, selection of the most appropriate target material is perhaps the most difficult because of the requisite fast and selective thermal release of minute amounts of the short-lived product atoms from the ISOL target in the presence of bulk amounts of target material. Experimental studies are under way at the Oak Ridge National Laboratory (ORNL) which are designed to measure the time evolution of implanted elements diffused from refractory target materials which are candidates for forming radioactive ion beams (RIBs) at the Holifield Radioactive Ion Beam Facility (HRIBF). The diffusion coefficients are derived by comparing experimental data with numerical solutions to a one-dimensional form of Fick's second equation for ion implanted distributions. In this report, we describe the experimental arrangement, experimental procedures, and provide time release data and diffusion coefficients for releasing ion implanted 37Cl from Zr 5Si 3 and 75As, 79Br, and 78Se from Zr 5Ge 3 and estimates of the diffusion coefficients for 35Cl, 63Cu, 65Cu, 69Ga, and 71Ga diffused from BN; 35Cl, 63Cu, 65Cu, 69Ga, 75As, and 78Se diffused from C; 35Cl, 68Cu, 69Ga, 75As, and 78Se diffused from Ta.

  17. Superheated water ion-exchange chromatography: an experimental approach for interpretation of separation selectivity in ion-exchange processes.

    Science.gov (United States)

    Shibukawa, Masami; Shimasaki, Tomomi; Saito, Shingo; Yarita, Takashi

    2009-10-01

    Cation-exchange selectivity for alkali and alkaline-earth metal ions and tetraalkylammonium ions on a strongly acidic sulfonic acid cation-exchange resin has been investigated in the temperature range of 40-175 degrees C using superheated water chromatography. Dependence of the distribution coefficient (ln KD) on the reciprocal of temperature (1/T) is not linear for most of the ions studied, and the selectivity coefficient for a pair of alkali metal ions or that of alkaline-earth metal ions approaches unity as temperature increases. On the other hand, the retention order of tetraalkylammonium ions is reversed at 160 degrees C or above when eluted with Na2SO4 aqueous solution and the larger ions are eluted faster than the smaller ones contrary to the retention order obtained at ambient temperature. The change in ion-exchange selectivity with temperature observed with superheated water chromatography has been discussed on the basis of the effect of temperature on hydration of the ions and specific adsorption or distribution of ionic species between the external solution and ion-exchange resin. In superheated water, the electrostatic interaction or association of the ions with the fixed ion becomes a predominant mechanism resulting in different separation selectivity from that obtained at ambient temperature.

  18. Poly(vinylidene fluoride)/SiO2 composite membranes prepared by electrospinning and their excellent properties for nonwoven separators for lithium-ion batteries

    Science.gov (United States)

    Zhang, Feng; Ma, Xilan; Cao, Chuanbao; Li, Jili; Zhu, Youqi

    2014-04-01

    PVdF/SiO2 composite nonwoven membranes exhibiting high safety (thermal stability), high ionic conductivity and excellent electrochemical performances are firstly prepared by electrospinning poly(vinylidene fluoride) (PVdF) homopolymer and silicon dioxide (SiO2) sol synchronously for the separators of lithium-ion batteries (LIBs). Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and hot oven tests show that the PVdF/SiO2 composite nonwoven membranes are thermally stable at a high temperature of 400 °C while the commercial Celgard 2400 PP membrane exhibits great shrinkage at 130 °C, indicating a superior thermal stability of PVdF/SiO2 composite nonwoven membranes than that of Celgard membrane. Moreover, the composite membrane exhibits fairly high ionic conductivity (7.47 × 10-3 S cm-1) that significantly improves the performance of LIBs. The PVdF/SiO2 composite membranes are also evaluated to have higher level of porosity (75-85%) and electrolyte uptake (571-646 wt%), lower interfacial resistance compared to the Celgard separator. The lithium-ion cell (using LiFePO4 cathode) assembled with the composite membrane exhibits more stable cycle performance, higher discharge capacity (159 mAh g-1) and excellent capacity retention which proves that they are promising candidates for separators of high performance rechargeable LIBs.

  19. Multicore-shell nanofiber architecture of polyimide/polyvinylidene fluoride blend for thermal and long-term stability of lithium ion battery separator

    Science.gov (United States)

    Park, Sejoon; Son, Chung Woo; Lee, Sungho; Kim, Dong Young; Park, Cheolmin; Eom, Kwang Sup; Fuller, Thomas F.; Joh, Han-Ik; Jo, Seong Mu

    2016-11-01

    Li-ion battery, separator, multicoreshell structure, thermal stability, long-term stability. A nanofibrous membrane with multiple cores of polyimide (PI) in the shell of polyvinylidene fluoride (PVdF) was prepared using a facile one-pot electrospinning technique with a single nozzle. Unique multicore-shell (MCS) structure of the electrospun composite fibers was obtained, which resulted from electrospinning a phase-separated polymer composite solution. Multiple PI core fibrils with high molecular orientation were well-embedded across the cross-section and contributed remarkable thermal stabilities to the MCS membrane. Thus, no outbreaks were found in its dimension and ionic resistance up to 200 and 250 °C, respectively. Moreover, the MCS membrane (at ~200 °C), as a lithium ion battery (LIB) separator, showed superior thermal and electrochemical stabilities compared with a widely used commercial separator (~120 °C). The average capacity decay rate of LIB for 500 cycles was calculated to be approximately 0.030 mAh/g/cycle. This value demonstrated exceptional long-term stability compared with commercial LIBs and with two other types (single core-shell and co-electrospun separators incorporating with functionalized TiO2) of PI/PVdF composite separators. The proper architecture and synergy effects of multiple PI nanofibrils as a thermally stable polymer in the PVdF shell as electrolyte compatible polymers are responsible for the superior thermal performance and long-term stability of the LIB.

  20. Cytotoxicity of glass ionomer cement on human exfoliated deciduous teeth stem cells correlates with released fluoride, strontium and aluminum ion concentrations

    Directory of Open Access Journals (Sweden)

    Kanjevac Tatjana V.

    2015-01-01

    Full Text Available Stem cells from human exfoliated deciduous teeth (SHED can be used as a cell-based therapy in regenerative medicine and in immunomodulation. Pulp from human deciduous teeth can be stored as a source of SHED. Glass ionomer cements (GICs are commonly used in restorative dentistry and in cavity lining. GICs have lower biocompatibility and are cytotoxic for dental pulp cells. In this study, seven commonly used GICs were tested for their cytotoxic effects on SHED, for their potential to arrest mitosis in cells and induce chromosome aberrations, and were compared with the effects of composite. Fuji II, Fuji VIII, Fuji IX, Fuji plus and Vitrebond had significantly higher cytotoxic effects on SHED than composite. Only SHEDs that have been treated with Fuji I, Fuji IX, Fuji plus and composite recovered the potential for proliferation, but no chromosome aberrations were found after treatment with GICs. The cytotoxic effects of GICs on SHEDs were in strong correlation with combined concentrations of released fluoride, aluminum and strontium ions. Fuji I exhibited the lowest activity towards SHEDs; it did not interrupt mitosis and did not induce chromosome aberrations, and was accompanied by the lowest levels of released F, Al and Sr ions. Projekat Ministarstva nauke Republike Srbije, br. ON175069, br. ON175071 i br. ON175103

  1. Closely packed x-poly(ethylene glycol diacrylate) coated polyetherimide/poly(vinylidene fluoride) fiber separators for lithium ion batteries with enhanced thermostability and improved electrolyte wettability

    Science.gov (United States)

    Zhai, Yunyun; Xiao, Ke; Yu, Jianyong; Ding, Bin

    2016-09-01

    The x-polyethylene glycol diacrylate (x-PEGDA) coated polyetherimide/polyvinylidene fluoride (PEI/PVdF) membranes are obtained by the facile combination of dip-coating and free radical polymerization of PEGDA on the electrospun PEI/PVdF fiber membranes. Successful cross-linking of PEGDA increases the average fibers diameter from 553 to 817 nm and reduces the packing density, which not only increases the tensile strength of x-PEGDA coated PEI/PVdF membranes, but also decreases the average pore diameter. Besides, the x-PEGDA coated PEI/PVdF membranes are endowed with good wettability, high electrolyte uptake, high ionic conductivity and improved electrochemical stability window because of the good affinity of PEI and PEGDA with liquid electrolyte. Benefiting from the synergetic effect of PEI and PVdF, the x-PEGDA coated PEI/PVdF membranes exhibit excellent thermal stability and nonflammability, which are beneficial for enhancing the safety of lithium ion batteries. More importantly, the x-PEGDA coated PEI/PVdF membranes based Li/LiFePO4 cell exhibits comparable cycling stability with capacity retention of 95.9% after 70 cycles and better rate capability compared with the Celgard membrane based cell. The results clearly demonstrate that the x-PEGDA coated PEI/PVdF membranes are the promising separator candidate with improved wettability and safety for next-generation lithium ion batteries.

  2. Multicore-shell nanofiber architecture of polyimide/polyvinylidene fluoride blend for thermal and long-term stability of lithium ion battery separator.

    Science.gov (United States)

    Park, Sejoon; Son, Chung Woo; Lee, Sungho; Kim, Dong Young; Park, Cheolmin; Eom, Kwang Sup; Fuller, Thomas F; Joh, Han-Ik; Jo, Seong Mu

    2016-11-11

    Li-ion battery, separator, multicoreshell structure, thermal stability, long-term stability. A nanofibrous membrane with multiple cores of polyimide (PI) in the shell of polyvinylidene fluoride (PVdF) was prepared using a facile one-pot electrospinning technique with a single nozzle. Unique multicore-shell (MCS) structure of the electrospun composite fibers was obtained, which resulted from electrospinning a phase-separated polymer composite solution. Multiple PI core fibrils with high molecular orientation were well-embedded across the cross-section and contributed remarkable thermal stabilities to the MCS membrane. Thus, no outbreaks were found in its dimension and ionic resistance up to 200 and 250 °C, respectively. Moreover, the MCS membrane (at ~200 °C), as a lithium ion battery (LIB) separator, showed superior thermal and electrochemical stabilities compared with a widely used commercial separator (~120 °C). The average capacity decay rate of LIB for 500 cycles was calculated to be approximately 0.030 mAh/g/cycle. This value demonstrated exceptional long-term stability compared with commercial LIBs and with two other types (single core-shell and co-electrospun separators incorporating with functionalized TiO2) of PI/PVdF composite separators. The proper architecture and synergy effects of multiple PI nanofibrils as a thermally stable polymer in the PVdF shell as electrolyte compatible polymers are responsible for the superior thermal performance and long-term stability of the LIB.

  3. Determination of fluoride in black, green and herbal teas by ionselective electrode using a standard-addition method

    Directory of Open Access Journals (Sweden)

    Mochammad Yuwono

    2005-06-01

    Full Text Available Tea leaves are very rich in fluoride, since tea plants take up fluoride from the soil and accumulate in its leaves. Some of this fluoride is released into the infusion, which is drunk as tea. Fluoride in tea could be beneficial for the prevention of dental caries, but it may result in excessive intake and lead to enamel fluorosis. The purpose of this work was to determine the fluoride levels in 12 different brands and types of tea by means of a computer-controlled ion-selective electrode potentiometry using a standard-addition method. It is a rapid method which showed good accuracy and precision. Fluoride contents of tea infusions after 5 min ranged from 0.95 to 4.73 mg/l for black teas; from 0.70 to 1.00 mg/l for green teas, and from 0.26 to 0.27 mg/l for herbal teas. It was concluded that black teas and green teas examined may be important contributors to the total daily fluoride intake. However, the ingestion of some black teas that were found to have high fluoride content by children at the age of risk to dental fluorosis should be avoided.

  4. Fluorous polymeric membranes for ionophore-based ion-selective potentiometry: how inert is Teflon AF?

    Science.gov (United States)

    Lai, Chun-Ze; Koseoglu, Secil S; Lugert, Elizabeth C; Boswell, Paul G; Rábai, József; Lodge, Timothy P; Bühlmann, Philippe

    2009-02-04

    Fluorous media are the least polar and polarizable condensed phases known. Their use as membrane materials considerably increases the selectivity and robustness of ion-selective electrodes (ISEs). In this research, a fluorous amorphous perfluoropolymer was used for the first time as a matrix for an ISE membrane. Electrodes for pH measurements with membranes composed of poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole]-co-poly(tetrafluoroethylene) (87% dioxole monomer content; known as Teflon AF2400) as polymer matrix, a linear perfluorooligoether as plasticizer, sodium tetrakis[3,5-bis(perfluorohexyl)phenyl]borate providing for ionic sites, and bis[(perfluorooctyl)propyl]-2,2,2-trifluoroethylamine as H+ ionophore were investigated. All electrodes had excellent potentiometric selectivities, showed Nernstian responses to H+ over a wide pH range, exhibited enhanced mechanical stability, and maintained their selectivity over at least 4 weeks. For membranes of low ionophore concentration, the polymer affected the sensor selectivity noticeably at polymer concentrations exceeding 15%. Also, the membrane resistance increased quite strongly at high polymer concentrations, which cannot be explained by the Mackie-Meares obstruction model. The selectivities and resistances depend on the polymer concentration because of a functional group associated with Teflon AF2400, with a concentration of one functional group per 854 monomer units of the polymer. In the fluorous environment of these membranes, this functional group binds to Na+, K+, Ca2+, and the unprotonated ionophore with binding constants of 10(3.5), 10(1.8), 10(6.8), and 10(4.4) M(-1), respectively. Potentiometric and spectroscopic evidence indicates that these functional groups are COOH groups formed by the hydrolysis of carboxylic acid fluoride (COF) groups originally present in Teflon AF2400. The use of higher ionophore concentrations removes the undesirable effect of these COOH groups almost completely

  5. "Borderline" fluorotic region in Serbia: correlations among fluoride in drinking water, biomarkers of exposure and dental fluorosis in schoolchildren.

    Science.gov (United States)

    Antonijevic, Evica; Mandinic, Zoran; Curcic, Marijana; Djukic-Cosic, Danijela; Milicevic, Nemanja; Ivanovic, Mirjana; Carevic, Momir; Antonijevic, Biljana

    2016-06-01

    This study explores relation between dental fluorosis occurrence in schoolchildren, residents of Ritopek, a small local community near Belgrade, and fluoride exposure via drinking water. Additionally, fluoride levels were determined in children's urine and hair samples, and efforts were made to correlate them with dental fluorosis. Dental fluorosis and caries prevalence were examined in a total of 52 schoolchildren aged 7-15 years (29 boys and 23 girls). Fluoride levels in three types of samples were analyzed using composite fluoride ion-selective electrode. Results showed high prevalence of dental fluorosis (34.6 %) and low prevalence of dental caries (23.1 %, mean DMFT 0.96) among children exposed to wide range of water fluoride levels (0.11-4.14 mg/L, n = 27). About 11 % of water samples exceeded 1.5 mg/L, a drinking-water quality guideline value for fluoride given by the World Health Organization (2006). Fluoride levels in urine and hair samples ranged between 0.07-2.59 (n = 48) and 1.07-19.83 mg/L (n = 33), respectively. Severity of dental fluorosis was positively and linearly correlated with fluoride levels in drinking water (r = 0.79). Fluoride levels in urine and hair were strongly and positively correlated with levels in drinking water (r = 0.92 and 0.94, respectively). Fluoride levels in hair samples appeared to be a potentially promising biomarker of fluoride intake via drinking water on one hand, and severity of dental fluorosis on the other hand. Based on community fluorosis index value of 0.58, dental fluorosis revealed in Ritopek can be considered as "borderline" public health issue.

  6. THE USE OF FLUORIDE CONTAINING MINERAL WATER IN WORT PRODUCTION

    Directory of Open Access Journals (Sweden)

    Gunka Yonkova

    2011-12-01

    Full Text Available The present work aims to study the quality of wort produced using fluoride containing mineral water. The results show that the mineral water has a negative impact on the enzymatic destruction of starch, proteins, color intensity and pH of the wort. The changes of pH during mashing process using tap and mineral water was studied. The lower acidity of wort obtained using mineral water didn’t change during the brewing process. The fluoride content of beer is lower than 5 mg.L-1 when wort is produced using mineral and tap water in 1:1 ratio and citric acid for pH correction. At the same time, the final degree of fermentation, α-amine nitrogen content and the intensity of color of produced wort are close to the control sample. The changes in fluoride ion concentration are monitored using ion-selective potentiometry. The fluoride content is decreased from 5.7 to 4.75 mg.L-1, the most intense change is observed during the mashing process.

  7. Analysis of fluoride concentration in solutions prepared at dispensing pharmacies

    Directory of Open Access Journals (Sweden)

    Eduardo Pizzatto

    2011-07-01

    Full Text Available Introduction: Fluoride plays an important role in oral health promotion and is considered important in dental caries prevention both in children and adults. Fluoride is widely used at high-risk conditions of caries, when the use of fluoride-containing mouthwashes is recommended, considering that fluoride itself reduces the risk of dental caries. Objective: To evaluate the fluoride concentration in solutions prepared at different dispensing pharmacies in the city of Curitiba – PR, Brazil. Material and methods: The analysis of fluoride concentration was preformed through Ion Chromatography method (DIONEX. Results: The results obtained through this analysis showed that all solutions presented fluoride concentration above that required in the dentist’s prescription, varying between 5.48% and 24.02% more fluoride, at absolute concentration. Conclusion: This finding highlights the increasing risk of fluoride acute intoxication in cases of accidental ingestion of the solution.

  8. The New Theory of Ion-Selective Electrodes

    Directory of Open Access Journals (Sweden)

    Ernõ Pungor

    2001-05-01

    Full Text Available The paper discusses the anomalies of the former interpretation of the working mechanism of the ion-selective electrodes. It was thorougly discussed why the Donnan experiment could not be applied as the theoretical background of glass electrodes. It was assumed according to the Donnan interpretation that the measurable potential is produced by the transfer of the primary ion through the membrane. Since the 1960s, the author and coworkers have been investigating the problem of what can be the reason for the potential response of the electrodes. Practical measurements in connection with the response time, surface hindered reactions etc. were interpreted. Furthermore, the energy problems according to the Gibbs theory using two electrode components were investigated. It was established that the electrodes on which chemical reactions may occur with the primary ion have a surface reaction as the chemical basis of the response. For electrodes that work on the principle of the lyotropic series, surface reactions are also involved, but their response is not always Nernstian. The energy demand is covered by the charge separation at the electrodesolution interface.

  9. Detection of Fluoride with Ion Chromatography and Effect of Water Negative Peak on it and Improvement Measures%离子色谱测氟离子与负水峰对其的影响及改善措施

    Institute of Scientific and Technical Information of China (English)

    王万童

    2012-01-01

    几种氟离子常见测试方法在本文中给予了介绍。由于离子色谱法测氟离子越来越受重视,针对其测氟离子的缺陷,重点研究了负水峰对离子色谱法测氟离子的影响,并提出了一些改善措施。%Several fluoride analysis methods were introduced. As the ion chromatography method to measure the flu- oride was paid more attention, for the defects of fluoride detection, the effect of water negative peak was studied and some improvement measures were put forward on ion chromatography.

  10. Fluoride assay methodology for carbonated beverages.

    Science.gov (United States)

    Heilman, Judith R; Levy, Steven M; Wefel, James S; Patterson, Kristine Y; Cutrufelli, Rena; Pehrsson, Pamela R; Holden, Joanne M

    2006-01-01

    The purpose of this paper was to review different methodological techniques used for the assessment of fluoride in carbonated beverages, and compare results using a fluoride ion electrode direct read method with and without a prior decarbonation treatment. The carbonated beverages in this study were either purchased locally at grocery stores in Iowa City, Iowa, or purchased as part of a national representative sampling approach included in the National Fluoride Database and Intake Assessment Study (NFDIAS). The samples were compared with and without a decarbonating process. Soda pop and beer samples were analyzed by removing a 1-ml sample and adding a 1-ml buffer solution. The fluoride concentration of the sample and buffer combination was then determined using a fluoride ion specific electrode. There was no significant difference in the fluoride concentration of the samples with or without prior decarbonation. The mean absolute difference between the soda pop group with and without decarbonation was 0.01 ppm F, while results from the beer samples showed variation of 0.00 to 0.02 parts per million fluoride (ppm F). These differences were not statistically significant for the soda pop or beer groups (P=.50 and P=.74, respectively). Whether or not decarbonation was conducted prior to analysis, the fluoride assay results were the same. Therefore, decarbonation of soda pop and beer was deemed unnecessary prior to fluoride analysis.

  11. A Rapid Method to Detect Milk Adulteration Using Selective Fluoride-electrode%氟离子选择电极法快速检测鲜奶掺假

    Institute of Scientific and Technical Information of China (English)

    闫瑞霞; 李胜利; 何玲; 李彦国; 田印荣

    2012-01-01

    采用氟离子选择电极法测定鲜奶中氟含量的变化,判断鲜奶是否掺假,进而探讨快速检验鲜牛奶掺假的一种新型方法.具体做法是按一定比例在纯鲜奶中分别兑入掺假物:奶牛场水、纯净水、食盐及淀粉,配成掺假奶.用氟离子选择电极法分别测量样品奶的电位值,观察掺假奶样品与纯鲜奶之间电位值差的变化,用以判断鲜奶是否掺假.%A novel and easy way, selective fluoride-electrode, was introduced in this paper to milk adulteration. Raw milk was proportionally adulterated with dairy effluent, purified water, salt and starch, thus the adulterated milk was grouped into Group 1 , Group 2, Group 3 and Group 4. By using selective fluoride-electrode method, the potential value of the sample milk was measured to observe the variation of its difference between the adulterated milk and the raw milk.

  12. Fluoride release from newly marketed fluoride varnishes.

    Science.gov (United States)

    Jablonowski, Beth L; Bartoloni, Joseph A; Hensley, Donna M; Vandewalle, Kraig S

    2012-03-01

    New fluoride varnishes have been marketed that reportedly release more fluoride (Enamel Pro) or release fluoride more slowly (Vanish XT). The purpose of this study was to compare the amount and rate of fluoride release of new fluoride varnishes with other traditional fluoride varnishes. Extracted molars were cut into block sections. The enamel surfaces of the sections were painted with Enamel Pro, Duraphat, Vanish, or Vanish XT fluoride varnishes. One group was not treated and served as a negative control. The tooth sections were immersed in artificial saliva. The concentration of fluoride in parts per million was measured after the first 30 minutes, daily for the first week, and weekly until the level was below the limit of detection. Fluoride release was plotted over time. Cumulative fluoride release and rate of release (slope) were analyzed using one-way ANOVA/Tukey (α = .05). Enamel Pro had the greatest cumulative fluoride release. There was no significant difference between Duraphat and Vanish. Vanish XT had the lowest cumulative fluoride release. The rate of fluoride release from 1 week to limit of detection was Enamel Pro > Vanish > Duraphat > Vanish XT. The two newly marketed fluoride varnishes (Enamel Pro and Vanish XT) had significantly different fluoride release from the two conventional fluoride varnishes (Duraphat and Vanish).

  13. The effect of fluoride and silicate ions on the coprecipitation of gadolinium with calcium in phosphoric and sulpho-phosphoric media

    Energy Technology Data Exchange (ETDEWEB)

    Bouhlassa, S.; Salhamen, F. [Univ. Mohammed V - Agdal, Rabat (Morocco). Lab. de Radiochimie

    2013-05-01

    This work was carried out with the aim to establish the effect of some impurities on the coprecipitation of gadolinium with calcium phosphate and gypsum. The tests were performed using the radioactive tracer technique to monitor the fate of gadolinium in various phosphoric and sulpho-phosphoric media containing fluoride and silicate ions as impurities. In 10{sup -2} to 10{sup -1} M NH{sub 4}H{sub 2}PO{sub 4} solution, the Gd(III) at a concentration of 10{sup -4} M is almost entirely precipitated as amorphous phosphate. However, the presence of H{sub 2}SO{sub 4} at C{sub H{sub 3SO{sub 4}}} {>=} 0.1 M, reduces the coprecipitation to less than 8 at. %, on average. The fluoride ions in solution, even at C{sub HF} {<=} 0.1 M, induce a reduction of coprecipitation of 10 to 30% according to HF concentration. In the media containing 10{sup -2} to 10{sup -1} M NH{sub 4}H{sub 2}PO{sub 4} and 10{sup -1} M H{sub 2}SO{sub 4}, the effect of HF is almost negligible in the absence of Si(IV); nevertheless, the presence of fluorosilicate in solution may contribute to the enhancement of the coprecipitation of the REE. The sulphuric acid (0.1 M) in phosphoric media (0.74 {<=} C{sub H{sub 3PO{sub 4}}} {<=} 4.44 M), leads to a significant coprecipitation of the REE (1.3 {+-} 0.2 {<=}D{sub Gd}{<=} 3.1 {+-} 0.5), whilst the addition of HF (0.1 M) to these media enhances the solubility of the REE (left angle D{sub Gd} right angle = 0.06 {+-} 0.01). XRD, IR spectroscopy and elemental analyses of the solid phases in conjunction with the variation of the distribution coefficient D indicate that the coprecipitation of the REE is likely controlled by heterovalent substitution of REE in gypsum and its precipitation as phosphate or fluorosilicate. (orig.)

  14. Electrical and electrochemical studies of poly(vinylidene fluoride)-clay nanocomposite gel polymer electrolytes for Li-ion batteries

    Science.gov (United States)

    Deka, M.; Kumar, A.

    A study is conducted on the electrical and electrochemical properties of nanocomposite polymer electrolytes based on intercalation of poly(vinylidene fluoride) (PVdF) polymer into the galleries of organically modified montmorillonite (MMT) clay. A solution intercalation technique is employed for nanocomposite formation with varying clay loading from 0 to 4 wt.%. X-ray diffraction results show the β phase formation of PVdF on intercalation. Transmission electron microscopy reveals the formation of partially exfoliated nanocomposites. The nanocomposites are soaked with 1 M LiClO 4 in a 1:1 (v/v) solution of propylene carbonate (PC) and diethyl carbonate (DEC) to obtain the required gel electrolytes. The structural conformation of the nanocomposite electrolytes is examined by Fourier transform infrared spectroscopy analysis. Examination with a.c. impedance spectroscopy reveals that the ionic conductivity of the nanocomposite gel polymer electrolytes increases with increase in clay loading and attains a maximum value of 2.3 × 10 -3 S cm -1 for a 4 wt.% clay loading at room temperature. The same composition exhibits enhancement in the electrochemical and interfacial properties as compared with that of a clay-free electrolyte system.

  15. Fluoridation Basics

    Science.gov (United States)

    ... level in water is not enough to prevent tooth decay; however, some groundwater and natural springs can have ... the tooth’s surface, or enamel. Water fluoridation prevents tooth decay by providing frequent and consistent contact with low ...

  16. Transport-limited water splitting at ion-selective interfaces during concentration polarization

    DEFF Research Database (Denmark)

    Nielsen, Christoffer Peder; Bruus, Henrik

    2014-01-01

    We present an analytical model of salt- and water-ion transport across an ion-selective interface based on an assumption of local equilibrium of the water-dissociation reaction. The model yields current-voltage characteristics and curves of water-ion current versus salt-ion current, which are in ...

  17. Assessment of fluoride concentration and daily intake by human from tea and herbal infusions.

    Science.gov (United States)

    Malinowska, E; Inkielewicz, I; Czarnowski, W; Szefer, P

    2008-03-01

    The fluoride content in infusions of commercially available black, green, oolong, pu-erh and white teas was determined by ion-selective electrode. Herbal infusions as well as instant tea and ready-to-drink tea beverages were also examined. It is found that brewing time (5, 10 and 30 min) does increase the fluoride content, which in infusions of black tea (5 min brewing) was higher than that in the other types of tea, with contents ranging between 0.32 and 4.54 mg/l for black tea to 0.37-0.54 mg/l for white tea and with even lower values for herbal tea infusions of 0.02-0.09 mg/l. On the basis of the results obtained, the daily intake of fluoride provided from tea and herbal beverages was estimated for an adult person and for children in comparison with the Polish SAI (Safe and Adequate Daily Intake) of fluoride which is strictly attributable to ADI (Acceptable Daily Intake). The fluoride intake resulted from the regular consumption of black tea infusions was raised as compared to the other types of teas as well as herbal teas. For adult and children tea drinkers consuming five cups of black tea per day the intake of fluoride will be in the range of 8.0-303% and 12-303% of the SAI, respectively. People are often exposed to multiple sources of fluoride, such as in food, water, air and excessive use of toothpaste. The control of tea quality is important to protect human against too high uptake of this element from black tea, which is the most popular beverage. Excessive intake of fluoride with black tea, especially in the regions with its high level in the drinking water, increases the risk of dental fluorosis in children during the years of tooth development. The long-term exposure to large amounts of fluoride can lead to potentially skeletal fluorosis (WHO, 1984).

  18. Urinary fluoride output in children following the use of a dual-fluoride varnish formulation

    Directory of Open Access Journals (Sweden)

    Kelly Polido Kaneshiro Olympio

    2009-06-01

    Full Text Available OBJECTIVE: This study evaluated the bioavailability of fluoride after topical application of a dual-fluoride varnish commercially available in Brazil, when compared to DuraphatTM. MATERIAL AND METHODS: The urinary fluoride output was evaluated in seven 5-year-old children after application of the fluoride varnishes, in two different phases. In the first phase (I, children received topical application of the fluoride varnish Duofluorid XII (2.92% fluorine, calcium fluoride + 2.71% fluorine, sodium fluoride, FGM TM. After 1-month interval (phase II, the same amount (0.2 mL of the fluoride varnish Duraphat (2.26% fluorine, sodium fluoride, ColgateTM was applied. Before each application all the volunteers brushed their teeth with placebo dentifrice for 7 days. Urinary collections were carried out 24 h prior up to 48 h after the applications. Fluoride intake from the diet was also estimated. Fluoride concentration in diet samples and urine was analyzed with the fluoride ion-specific electrode and a miniature calomel reference electrode coupled to a potentiometer. Data were tested by ANOVA and Tukey's post hoc test (p<0.05. RESULTS: There were significant differences in the urinary fluoride output between phases I and II. The use of Duofluorid XII did not significantly increase the urinary fluoride output, when compared to baseline levels. The application of Duraphat caused a transitory increase in the urinary fluoride output, returning to baseline levels 48 h after its use. CONCLUSIONS: The tested varnish formulation, which has been shown to be effective in in vitro studies, also can be considered safe.

  19. Influence of methionine and vitamin E on fluoride concentration in bones and teeth of rats exposed to sodium fluoride in drinking water.

    Science.gov (United States)

    Błaszczyk, Iwona; Birkner, Ewa; Gutowska, Izabela; Romuk, Ewa; Chlubek, Dariusz

    2012-06-01

    Increased exposure to fluorine-containing compounds leads to accumulation of fluorides in hard tissues of bones and teeth, which may result in numerous skeletal and dental disorders. This study evaluates the influence of methionine and vitamin E on fluoride concentration in bones and teeth of rats subjected to long-term exposure to sodium fluoride in drinking water. The study was conducted in 30 3-month-old female Wistar FL rats. The animals were divided into five groups, six rats per group. The control group consisted of rats receiving only distilled water as drinking water. All other groups received NaF in the amount of 10 mg/kg of body mass/day in their drinking water. In addition, respective animal groups received: NaF + Met group--10 mg of methionine/kg of body mass/day, NaF + Met + E group--10 mg of methionine/kg of body mass/day and 3 mg of vitamin E (tocopheroli acetas)/rat/day and NaF + E group--3 mg of vitamin E/rat/day. Femoral bones and incisor teeth were collected for the study, and the fluoride concentration was determined using a fluoride ion-selective electrode. Fluoride concentration in both bones and teeth was found to be higher in the NaF and NaF + Met groups compared to the control group. In groups NaF + Met + E and NaF + E, the study material contained much lower fluoride concentration compared to the NaF group, while the effect was more prominent in the NaF + E group. The results of the studies indicate that methionine and vitamin E have opposite effects on accumulation of fluorides in hard tissue in rats. By stimulating fluoride accumulation, methionine reduces the adverse effect of fluorides on soft tissue, while vitamin E, which prevents excessive accumulation of fluorides in bones and teeth, protects these tissues from fluorosis. Therefore, it seems that combined application of both compounds would be optimal for the prevention of the adverse effects of chronic fluoride intoxication.

  20. Vacuum Pyrolysis of Fluoride Retention in Electrode Active Material of Lithium Ion Battery%废旧锂电池电极活性材料真空热解固氟研究

    Institute of Scientific and Technical Information of China (English)

    谢光炎; 凌云; 孙水裕

    2012-01-01

    以废旧锂离子电池电极活性材料为研究对象,在真空热解过程中加入CaO作为固氟剂,用以吸收电极活性材料在真空热解的回收工艺中产生的氟磷化合物,能有效减轻二次污染.研究了温度、CaO添加量、停留时间等热解条件对真空热解固氟效果的影响.结果表明固氟效果随温度的增加而增加,在温度500℃以上变化不大,并略有下降;CaO添加量对固氟效果有促进作用,30%可达到很高的固氟效果;30 min的停留时间对于含氟化合物的分解已经足够.得到CaO固氟工序的最佳操作参数:CaO添加量30%左右,温度500~600℃,停留时间30 min.%With electrode active materials of lithium ion batteries (LIBs)as research objects, CaO as a fluoride retention additive in the vacuum pyrolysis process, fluoride phosphorus compounds produced in the vacuum pyrolysis of electrode active materials can be effectively absorbed, which would reduce the secondary pollution. Effects of pyrolysis conditions such as pyrolysis temperature, CaO addition and residence time on fluoride retention were investigated. Results showed that effects of fluoride retention increased with temperature, and effect of fluoride retention changed a little and slightly decreased above 500 t. CaO addition is helpful to fluoride retention, with 30% of addition quantity to a satisfactory result. 30min residence time for fluoride and phosphorus compound decomposition is sufficient. The optimum conditions of fluoride and phosphorus retention by CaO were 30% CaO addition quantity, temperature 500-600 ℃ and residence time 30 min.

  1. Effect of one-bottle adhesive systems on the fluoride release of a resin-modified glass ionomer Efeito dos sistemas adesivos de frasco único na liberação de flúor de um cimento de ionômero de vidro modificado por resina

    Directory of Open Access Journals (Sweden)

    Linda Wang

    2004-03-01

    Full Text Available A dhesive systems associated to resin-modified glass ionomer cements are employed for the achievement of a higher bond strength to dentin. Despite this benefit, other properties should not be damaged. This study aimed at evaluating the short-time fluoride release of a resin-modified glass ionomer cement coated with two one-bottle adhesive systems in a pH cycling system. Four combinations were investigated: G1: Vitremer (V; G2: Vitremer + Primer (VP; G3: Vitremer + Single Bond (VSB and G4: Vitremer + Prime & Bond 2.1 (VPB. SB is a fluoride-free and PB is a fluoride-containing system. After preparation of the Vitremer specimens, two coats of the selected adhesive system were carefully applied and light-cured. Specimens were immersed in demineralizing solution for 6 hours followed by immersion in remineralizing solution for 18 hours, totalizing the 15-day cycle. All groups released fluoride in a similar pattern, with a greater release in the beginning and decreasing with time. VP showed the greatest fluoride release, followed by V, with no statistical difference. VSB and VPB released less fluoride compared to V and VP, with statistical difference. Regardless the one-bottle adhesive system, application of coating decreased the fluoride release from the resin-modified glass ionomer cements. This suggests that this combination would reduce the beneficial effect of the restorative material to the walls around the restoration.Sistemas adesivos são associados aos cimentos de ionômero de vidro modificados por resina para a obtenção de maior resistência adesiva à dentina. Apesar deste benefício, outras propriedades não devem ser prejudicadas. Este estudo se propôs a avaliar a liberação de flúor a curto prazo de um cimento de ionômero de vidro modificado por resina coberto com dois diferentes sistemas adesivos em um modelo de ciclagem de pH. Quatro associações foram testadas: G1: Vitremer (V; G2: Vitremer + Primer (VP; G3: Vitremer + Single

  2. A microporous gel electrolyte based on poly(vinylidene fluoride-co-hexafluoropropylene)/fully cyanoethylated cellulose derivative blend for lithium-ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Ren Zhong [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Liu Yuyan [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: liuyy@hit.edu.cn; Sun Kening; Zhou Xiaoliang; Zhang Naiqing [Science Reseach Center, Harbin Institute of Technology, Harbin 150001 (China)

    2009-02-15

    A gel polymer electrolyte based on the blend of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and fully cyanoethylated cellulose derivative (DH-4-CN) was prepared and characterized. Thermal, mechanical, swelling, liquid electrolyte retention and electrochemical properties, as well as microstructures of the prepared polymer electrolytes, were investigated using thermogravimetric analysis, electrochemical impedance spectroscopy, linear sweep voltammetry, and scanning electron microscopy. The results showed that the addition of DH-4-CN could obviously improve the conductivity of PVDF-HFP based electrolyte. The maximum ionic conductivity of 4.36 mS cm{sup -1} at 20 deg. C can be obtained for PVDF-HFP/DH-4-CN 14:1 in the presence of 1 M LiPF{sub 6} in EC and DMC (1:1, w/w). The dry blend membranes exhibit excellent thermal behavior. All the blend electrolytes are electrochemically stable up to about 4.8 V vs. Li/Li{sup +} for all compositions. The results reveal that the composite polymer electrolyte qualifies as a potential application in lithium-ion battery.

  3. Preparation and characterization of lithium ion conducting polymer electrolytes based on a blend of poly(vinylidene fluoride-co-hexafluoropropylene and poly(methyl methacrylate

    Directory of Open Access Journals (Sweden)

    Merhawi Abreha Gebreyesus

    2016-07-01

    Full Text Available Ion conducting polymer electrolytes composed of poly(vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP, poly(methyl methacrylate (PMMA and lithium triflate (LiTf were prepared using the solution casting method. Structural change and complex formation in the blend electrolyte systems were confirmed from the X-ray diffraction (XRD, Fourier transform infrared (FTIR spectroscopy and scanning electron microscopy (SEM studies. Thermal properties of the samples were investigated by the differential scanning calorimetry (DSC technique. The ionic conductivity of these polymer electrolytes was studied by impedance spectroscopy at various temperatures ranging from 303–393 K. The results reveal that the ionic conductivity of the polymer blend electrolytes depends on the PVdF-HFP:PMMA composition as well as the temperature. Maximum room temperature conductivity of 7.4×10−5 S cm−1 was achieved with 22.5 wt.% PMMA. The blending of PVdF-HFP with PMMA improved the thermal stability and ionic conductivity of the polymer electrolyte. Estimated transference numbers suggest the charge transport is predominantly ionic.

  4. Sulfonic Acid- and Lithium Sulfonate-Grafted Poly(Vinylidene Fluoride) Electrospun Mats As Ionic Liquid Host for Electrochromic Device and Lithium-Ion Battery.

    Science.gov (United States)

    Zhou, Rui; Liu, Wanshuang; Leong, Yew Wei; Xu, Jianwei; Lu, Xuehong

    2015-08-05

    Electrospun polymer nanofibrous mats loaded with ionic liquids (ILs) are promising nonvolatile electrolytes with high ionic conductivity. The large cations of ILs are, however, difficult to diffuse into solid electrodes, making them unappealing for application in some electrochemical devices. To address this issue, a new strategy is used to introduce proton conduction into an IL-based electrolyte. Poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) copolymer is functionalized with sulfonic acid through covalent attachment of taurine. The sulfonic acid-grafted P(VDF-HFP) electrospun mats consist of interconnected nanofibers, leading to remarkable improvement in dimensional stability of the mats. IL-based polymer electrolytes are prepared by immersing the modified mats in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM(+)BF4(-)). It is found that the SO3(-) groups can have Lewis acid-base interactions with the cations (BMIM(+)) of IL to promote the dissociation of ILs, and provide additional proton conduction, resulting in significantly improved ionic conductivity. Using this novel electrolyte, polyaniline-based electrochromic devices show higher transmittance contrast and faster switching behavior. Furthermore, the sulfonic acid-grafted P(VDF-HFP) electrospun mats can also be lithiated, giving additional lithium ion conduction for the IL-based electrolyte, with which Li/LiCoO2 batteries display enhanced C-rate performance.

  5. Preparation and characterization of lithium ion conducting polymer electrolytes based on a blend of poly(vinylidene fluoride-co-hexafluoropropylene) and poly(methyl methacrylate).

    Science.gov (United States)

    Gebreyesus, Merhawi Abreha; Purushotham, Y; Kumar, J Siva

    2016-07-01

    Ion conducting polymer electrolytes composed of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), poly(methyl methacrylate) (PMMA) and lithium triflate (LiTf) were prepared using the solution casting method. Structural change and complex formation in the blend electrolyte systems were confirmed from the X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) studies. Thermal properties of the samples were investigated by the differential scanning calorimetry (DSC) technique. The ionic conductivity of these polymer electrolytes was studied by impedance spectroscopy at various temperatures ranging from 303-393 K. The results reveal that the ionic conductivity of the polymer blend electrolytes depends on the PVdF-HFP:PMMA composition as well as the temperature. Maximum room temperature conductivity of [Formula: see text] S cm(-1) was achieved with 22.5 wt.% PMMA. The blending of PVdF-HFP with PMMA improved the thermal stability and ionic conductivity of the polymer electrolyte. Estimated transference numbers suggest the charge transport is predominantly ionic.

  6. Luminal oxidants selectively modulate electrogenic ion transport in rat colon

    Institute of Scientific and Technical Information of China (English)

    Julio M Mayol; Yolanda Adame-Navarrete; Pilar Alarma-Estrany; Elena Molina-Roldan; Fernando Huete-Toral; Jesus A Fernandez-Represa

    2006-01-01

    AIM: To investigate the effects of luminal exposure to H2O2 and two related thiol oxidizing agents on basal and stimulated chloride secretion in native colon using electrophysiological and pharmacological approaches.METHODS: Unstripped rat distal colon segments were mounted in Ussing chambers. Potential difference, cal culated resistance and short-circuit current across unstripped colon segments were monitored with a dual voltage/current clamp. Paracellular permeability was assessed by measuring the mucosa-to-serosa flux of a fluorescent probe (FITC).RESULTS: Luminal exposure to hydrogen peroxide transitorily stimulated chloride secretion without altering barrier function. This stimulatory effect could be blocked by basolateral atropine but not indomethacin. The cysteine and methionine oxidizing compounds, phenylarsine oxide and chloramine T respectively, mimicked the effect of H2O2, except for a drop in transcolonic resistance after 30 min. In contrast to the observed stimulatory effect on basal secretion, cAMP-stimulated electrogenic ion trans port was blunted by luminal H2O2. However, the Ca2+-activated response remained unchanged.CONCLUSION: H2O2 may be an important selective modulator of intestinal ion and water secretion in certain pathologic conditions such as inflammation or ischemiareperfusion by multiple mechanisms.

  7. A novel ion selective sensor for promethium determination

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Vinod K., E-mail: vinodfcy@iitr.ernet.in [Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247 667 (India); Chemistry Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Jain, Rajeev [School of Studies in Chemistry, Jiwaji University, Gwalior 474011 (India); Hamdan, A.J. [Chemistry Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Agarwal, Shilpi [School of Studies in Chemistry, Jiwaji University, Gwalior 474011 (India); Bharti, Arvind K. [Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247 667 (India)

    2010-11-29

    This is a first promethium{sup 145} ion-selective sensor based on the comparative study of two Schiff base ligands (X{sub 1} and X{sub 2}) as neutral ionophores. Effect of various plasticizers: 2-nitrophenyloctylether (o-NPOE), dibutyl phosphonate (DBP), dioctylphthalate (DOP), tri-(2-ethylhexyl) phosphate (TEHP), dibutyl butylphosphonate (DBBP), chloronaphthalene (CN) and anion excluders: potassium tetrakis (p-chloropheny1) borate (KTpClPB), sodiumtetraphenylborate (NaTPB) and oleic acid (OA) have been studied. The membrane with a composition of ionophore (X{sub 1}/X{sub 2}):KTpClPB:PVC:o-NPOE (w/w, %) in the ratio of 5:5:30:60 exhibited best performance. The best responsive membrane sensors (8 and 21) exhibited working concentration range of 4.5 x 10{sup -7}-1.0 x 10{sup -2} M and 3.5 x 10{sup -6}-1.0 x 10{sup -2} M with a detection limits of 3.2 x 10{sup -7} M and 2.3 x 10{sup -6} M and Nernstian slopes of 20.0 {+-} 0.5, 19.5 {+-} 0.5 mV decade{sup -1} of activity, respectively. The sensor no. 8 works satisfactorily in partially non-aqueous media up to 10% (v/v) content of methanol, ethanol and acetonitrile. Analytical application of the proposed sensor has been demonstrated in determination of promethium (III) ions in spiked water samples.

  8. Fluoride export (FEX) proteins from fungi, plants and animals are 'single barreled' channels containing one functional and one vestigial ion pore.

    Science.gov (United States)

    Berbasova, Tetyana; Nallur, Sunitha; Sells, Taylor; Smith, Kathryn D; Gordon, Patricia B; Tausta, Susan Lori; Strobel, Scott A

    2017-01-01

    The fluoride export protein (FEX) in yeast and other fungi provides tolerance to fluoride (F-), an environmentally ubiquitous anion. FEX efficiently eliminates intracellular fluoride that otherwise would accumulate at toxic concentrations. The FEX homolog in bacteria, Fluc, is a 'double-barreled' channel formed by dimerization of two identical or similar subunits. FEX in yeast and other eukaryotes is a monomer resulting from covalent fusion of the two subunits. As a result, both potential fluoride pores are created from different parts of the same protein. Here we identify FEX proteins from two multicellular eukaryotes, a plant Arabidopsis thaliana and an animal Amphimedon queenslandica, by demonstrating significant fluoride tolerance when these proteins are heterologously expressed in the yeast Saccharomyces cerevisiae. Residues important for eukaryotic FEX function were determined by phylogenetic sequence alignment and functional analysis using a yeast growth assay. Key residues of the fluoride channel are conserved in only one of the two potential fluoride-transporting pores. FEX activity is abolished upon mutation of residues in this conserved pore, suggesting that only one of the pores is functional. The same topology is conserved for the newly identified FEX proteins from plant and animal. These data suggest that FEX family of fluoride channels in eukaryotes are 'single-barreled' transporters containing one functional pore and a second non-functional vestigial remnant of a homologous gene fusion event.

  9. Hydrophobic sodium fluoride-based nanocrystals doped with lanthanide ions: assessment of in vitro toxicity to human blood lymphocytes and phagocytes.

    Science.gov (United States)

    Sojka, Bartlomiej; Kuricova, Miroslava; Liskova, Aurelia; Bartusova, Maria; Banski, Mateusz; Misiewicz, Jan; Dusinska, Maria; Horvathova, Mira; Jahnova, Eva; Ilavska, Silvia; Szabova, Michaela; Rollerova, Eva; Podhorodecki, Artur; Tulinska, Jana

    2014-11-01

    In vitro immunotoxicity of hydrophobic sodium fluoride-based nanocrystals (NCs) doped with lanthanide ions was examined in this study. Although there is already a significant amount of optical and structural data on NaYF4 NCs, data on safety assessment are missing. Therefore, peripheral whole blood from human volunteers was used to evaluate the effect of 25 and 30 nm hydrophobic NaYF4 NCs dissolved in cyclohexane (CH) on lymphocytes, and of 10 nm NaYF4 NCs on phagocytes. In the concentration range 0.12-75 µg cm(-2) (0.17-106 µg ml(-1) ), both 25 and 30nm NaYF4 NCs did not induce cytotoxicity when measured as incorporation of [(3) H]-thymidine into DNA. Assessment of lymphocyte function showed significant suppression of the proliferative activity of T-lymphocytes and T-dependent B-cell response in peripheral blood cultures (n = 7) stimulated in vitro with mitogens phytohemagglutinin (PHA) and pokeweed (PWM) (PHA > PWM). No clear dose-response effect was observed. Phagocytic activity and respiratory burst of leukocytes (n = 5-8) were generally less affected. A dose-dependent suppression of phagocytic activity of granulocytes in cultures treated with 25 nm NCs was observed (vs. medium control). A decrease in phagocytic activity of monocytes was found in cells exposed to higher doses of 10 and 30 nm NCs. The respiratory burst of phagocytes was significantly decreased by exposure to the middle dose of 30 nm NCs only. In conclusion, our results demonstrate immunotoxic effects of hydrophobic NaYF4 NCs doped with lanthanide ions to lymphocytes and to lesser extent to phagocytes. Further research needs to be done, particularly faze transfer of hydrophobic NCs to hydrophilic ones, to eliminate the solvent effect.

  10. Ion sponge: a 3-dimentional array of quadrupole ion traps for trapping and mass-selectively processing ions in gas phase.

    Science.gov (United States)

    Xu, Wei; Li, Linfan; Zhou, Xiaoyu; Ouyang, Zheng

    2014-05-01

    In this study, the concept of ion sponge has been explored for developing 3D arrays of large numbers of ion traps but with simple configurations. An ion sponge device with 484 trapping units in a volume of 10 × 10 × 3.2 cm has been constructed by simply stacking 9 meshes together. A single rf was used for trapping ions and mass-selective ion processing. The ion sponge provides a large trapping capacity and is highly transparent for transfer of ions, neutrals, and photons for gas phase ion processing. Multiple layers of quadrupole ion traps, with 121 trapping units in each layer, can operate as a single device for MS or MS/MS analysis, or as a series of mass-selective trapping devices with interlayer ion transfers facilitated by AC and DC voltages. Automatic sorting of ions to different trapping layers based on their mass-to-charge (m/z) ratios was achieved with traps of different sizes. Tandem-in-space MS/MS has also been demonstrated with precursor ions and fragment ions trapped in separate locations.

  11. From unsuccessful H2-activation with FLPs containing B(Ohfip)3 to a systematic evaluation of the Lewis acidity of 33 Lewis acids based on fluoride, chloride, hydride and methyl ion affinities.

    Science.gov (United States)

    Böhrer, Hannes; Trapp, Nils; Himmel, Daniel; Schleep, Mario; Krossing, Ingo

    2015-04-28

    The possibility of obtaining frustrated Lewis pairs (FLPs) suitable for H2-activation based on the Lewis acid B(Ohfip)3 1 (Ohfip = OC(H)(CF3)2) was investigated. In this context, the crystal structure of 1 as well as the crystal structure of the very weak adduct 1·NCMe was determined. When reacting solutions of 1 with H2 (1 bar) and selected phosphanes, amines, pyridines and N-heterocyclic carbenes, dihydrogen activation was never observed. Without H2, adduct formation with 1 was observed to be an equilibrium process, regardless of the Lewis base adduct. Thus, the thermodynamics of H2 activation of 1 in comparison with the well-known B(C6F5)3 was analyzed using DFT calculations in the gas phase and different solvents (CH2Cl2, ortho-difluorobenzene and acetonitrile). These investigations indicated that FLP chemistry based on 1 is considerably less favored than that with B(C6F5)3. This is in agreement with control NMR experiments indicating hydride transfer from [H-B(Ohfip)3](-) upon reaction with B(C6F5)3, giving [H-B(C6F5)3](-) and B(Ohfip)3 in toluene and also MeCN. Induced by these unsuccessful reactions, the Lewis acidity towards HSAB hard and soft ions was investigated for gaining a deeper insight. A unified reference system based on the trimethylsilyl compounds Me3Si-Y (Y = F, Cl, H, Me) and their respective ions Me3Si(+)/Y(-) calculated at the G3 level was chosen as the anchor point. The individual ion affinities were then assessed based on subsequent isodesmic reactions calculated at a much less expensive level (RI-)BP86/SV(P). This method was validated by systematic calculations of smaller reference systems at the frozen core CCSD(T) level with correlation effects extrapolated to a full quadruple-ζ basis. Overall, 33 common and frequently used Lewis acids were ranked with respect to their FIA, CIA, HIA and MIA (fluoride/chloride/hydride/methyl ion affinity).

  12. [Enamel fluoride uptake following fluoride application and fluoride precipitation].

    Science.gov (United States)

    Buchalla, Wolfgang; Lennon, Aine M; Trage, Katrin; Becker, Klaus; Attin, Thomas

    2007-01-01

    This study is on fluoride uptake into enamel following fluoride precipitation with calcium hydroxide. Five specimens each from 12 bovine incisors were polished, covered with a salivary pellicle, and distributed into five groups (n=12). A fluoride solution (43,500 ppm F from magnesiumfluorosilicate, copper-(II)-fluorosilicate and sodium-fluoride, pH 2; Tiefenfluorid Touchierlösung, Humanchemie) and Ca(OH)2-solution (Tiefenfluorid Nachtouchierlösung) were applied subsequently in group TN. "Touchierlosung" only was used in group T, sodium-fluoride (43,500 ppm F, pH 2) in group NaF, and aminefluoride (Elmex fluid, 10,000 ppm F, pH 4) in group EF. No fluoride was used in group NK (negative control). Following rinsing and 24 h storage in artificial saliva surface KOH-soluble fluoride content (KOHF), and structurally bound fluoride content (SBF) from three layers (0-33, 33-66 and 66-99 pm) was determined by fluoride electrode procedures. KOHF (median in microg/cm2) of NK was below the lower limit of quantification of the fluoride electrode. The other group values were significantly higher (Mann-Whitney test, p precipitation reaction with Ca(OH)2 following fluoridation did not increase enamel fluoride uptake.

  13. Laboratory Evaluation of Ion-Selective Electrodes for Simultaneous Analysis of Macronutrients in Hydroponic Solution

    Science.gov (United States)

    Automated sensing of macronutrients in hydroponic solution would allow more efficient management of nutrients for crop growth in closed hydroponic systems. Ion-selective microelectrode technology requires an ion-selective membrane or a solid metal material that responds selectively to one analyte in...

  14. Distribution of fluoride in groundwater of Maku area, northwest of Iran

    Science.gov (United States)

    Asghari Moghaddam, Asghar; Fijani, Elham

    2008-11-01

    High fluoride groundwater occurs in Maku area, in the north of West Azarbaijan province, northwest of Iran. Groundwater is the main source of drinking water for the area residents. Groundwater samples were collected from 72 selected points including 40 basaltic and 32 nonbasaltic springs and wells, in two stages, during June and August 2006. The areas with high fluoride concentrations have been identified, and the possible causes for its variation have been investigated. Regional hydrogeochemical investigation indicates that water-rock interaction is probably the main reason for the high concentration of ions in groundwater. The concentration of F- in groundwater is positively correlated with that of HCO3 - and Na+, indicating that groundwater with high HCO3 - and Na+ concentrations help to dissolve some fluoride-rich minerals. All of the water samples, collected from the basaltic areas do not meet the water quality standards for fluoride concentration and some other parameters. Hence, it is not suitable for consumption without any prior treatment. Inhabitants of the area that obtain their drinking water supplies from basaltic springs and wells are suffering from dental fluorosis. The population of the study area is at a high risk due to excessive fluoride intake especially when they are unaware of the amount of fluoride being ingested due to lack of awareness.

  15. Exraction and separation of CERIUM(IV)/FLUORINE in fluoride-bearing cerium sulfate solution with fluoride coordination agent

    OpenAIRE

    Li, Y; J. G. He; X. X. Xue; Ru, H. Q.; X. W. Huang; Yang, H.

    2014-01-01

    In this paper the extraction and separation of cerium/fluorine in fluoride-bearing cerium sulfate solution with fluoride coordination agent has been studied. The UV-vis spectra suggest that Zr6+ and Al3+ can scrub the F- from [CeF2] 2+ complex. The separation and conductivity studies show that aluminum salt is the most suitable fluoride coordination agent, and an ion-exchange reaction is involved between Ce4+/ [CeF2] 2+ and hydrogen ion.

  16. Primary Discussion on the Preparation of the Li- ion Batteries Separator Based on the Poly( vinylidene fluoride)%聚偏氟乙烯制备锂离子电池隔膜初探

    Institute of Scientific and Technical Information of China (English)

    周丕严

    2012-01-01

    The status and problems of the Li - ion batteries separator were reviewed. The new materials for preparation of the Li - ion batteries separator and their development status were summarized. The structural characteristics and performance requirements of Li - ion batteries separator were introduced. The preparation and modifi- cation methods of Li - ion batteries separator based on the poly ( vinylidene fluoride) were preliminarily studied.%综述了锂离子电池隔膜的现状及其存在的问题,以及制备锂离子电池隔膜的新材料与发展现状;介绍了锂离子电池隔膜的结构特点与性能要求;对聚偏氟乙烯制备锂离子电池隔膜的方法及其改性技术进行了初步的探讨。

  17. Assessment of fluoride level in groundwater and prevalence of dental fluorosis in Didwana block of Nagaur district, Central Rajasthan, India.

    Science.gov (United States)

    Arif, M; Husain, I; Hussain, J; Kumar, S

    2013-10-01

    In India, for the high concentration of fluoride in groundwater, people are at risk of dental fluorosis. The problem is common in various states of India. The condition in Rajasthan is worse where all districts have such a problem. To study the fluoride concentration in groundwater and prevalence of dental fluorosis in Didwana block of Nagaur district, Central Rajasthan, India. The fluoride concentration in water of 54 villages was measured electrochemically, using fluoride ion selective electrode. Dental fluorosis was assessed in 1136 people residing in study area by Dean's classification for dental fluorosis. The fluoride concentration in groundwater in studied sites ranged from 0.5 to 8.5 mg/L. The concentration of fluoride was more than the maximum permissible limit set by WHO and Bureau of Indian Standards (1 mg/L) in 48 groundwater sources. Of 1136 people studied, 788 (69.4%; 95% CI: 66.7%-72.1%) had dental fluoros---252 had mild and 74 had severe dental fluorosis. High level of fluoride in drinking water of Didwana block of Nagaur district, Central Rajasthan, India, causes dental fluorosis in most people in the region and is an important health problem that needs prompt attention.

  18. Assessment of Fluoride Level in Groundwater and Prevalence of Dental Fluorosis in Didwana Block of Nagaur District, Central Rajasthan, India

    Directory of Open Access Journals (Sweden)

    S Kumar

    2013-10-01

    Full Text Available Background: In India, for the high concentration of fluoride in groundwater, people are at risk of dental fluorosis. The problem is common in various states of India. The condition in Rajasthan is worse where all districts have such a problem.Objective: To study the fluoride concentration in groundwater and prevalence of dental fluorosis in Didwana block of Nagaur district, Central Rajasthan, India.Methods: The fluoride concentration in water of 54 villages was measured electrochemically, using fluoride ion selective electrode. Dental fluorosis was assessed in 1136 people residing in study area by Dean's classification for dental fluorosis.Results: The fluoride concentration in groundwater in studied sites ranged from 0.5 to 8.5 mg/L. The concentration of fluoride was more than the maximum permissible limit set by WHO and Bureau of Indian Standards (1 mg/L in 48 groundwater sources. Of 1136 people studied, 788 (69.4%; 95% CI: 66.7%–72.1% had dental fluorosis—252 had mild and 74 had severe dental fluorosis.Conclusion: High level of fluoride in drinking water of Didwana block of Nagaur district, Central Rajasthan, India, causes dental fluorosis in most people in the region and is an important health problem that needs prompt attention.

  19. Fluoride-containing bioactive glasses: Glass design, structure, bioactivity, cellular interactions, and recent developments

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Furqan A., E-mail: furqan.ali.shah@biomaterials.gu.se

    2016-01-01

    Bioactive glasses (BGs) are known to bond to both hard and soft tissues. Upon exposure to an aqueous environment, BG undergoes ion exchange, hydrolysis, selective dissolution and precipitation of an apatite layer on their surface, which elicits an interfacial biological response resulting in bioactive fixation, inhibiting further dissolution of the glass, and preventing complete resorption of the material. Fluorine is considered one of the most effective in-vivo bone anabolic factors. In low concentrations, fluoride ions (F{sup −}) increase bone mass and mineral density, improve the resistance of the apatite structure to acid attack, and have well documented antibacterial properties. F{sup −} ions may be incorporated into the glass in the form of calcium fluoride (CaF{sub 2}) either by part-substitution of network modifier oxides, or by maintaining the ratios of the other constituents relatively constant. Fluoride-containing bioactive glasses (FBGs) enhance and control osteoblast proliferation, differentiation and mineralisation. And with their ability to release fluoride locally, FBGs make interesting candidates for various clinical applications, dentinal tubule occlusion in the treatment of dentin hypersensitivity. This paper reviews the chemistry of FBGs and the influence of F{sup −} incorporation on the thermal properties, bioactivity, and cytotoxicity; and novel glass compositions for improved mechanical properties, processing, and bioactive potential. - Highlights: • Fluoride ions form charged CaF{sup +} species rather than Si–F bonds. • Fluoride incorporation lowers glass transition and crystallisation temperatures. • Oxynitride and oxyfluoronitride glasses with superior mechanical properties • Mixed-alkali and alkali-free compositions with better processing characteristics.

  20. [Simultaneous photometric determination of covalently bound fluorine and fluoride ion contamination adsorbed on drugs in the low ppm range after alkaline pulping].

    Science.gov (United States)

    Seeling, A; Dahse, Th; Oelschläger, H

    2003-12-01

    The simultaneous determination of fluorine resulting from inorganic fluoride as well as fluorine-containing solvents adsorbed to drugs was achieved in the 0.1-30 ppm range by a combination of decomposition with magnesium oxide at 800 degrees C and steam distillation of the resulting fluoride followed by photometric measurement of the aminomethylalizarindiacetic acid-cerium(III) complex at 620 nm. The inevitable loss of fluoride occurring during the decomposition and distillation processes was corrected using factors derived from authorized calibrations. The method was validated using glucose contaminated with dexamethasone which contains 4.84% fluorine per molecule.

  1. A fluoride release-adsorption-release system applied to fluoride-releasing restorative materials.

    Science.gov (United States)

    Suljak, J P; Hatibovic-Kofman, S

    1996-09-01

    This investigation compared the initial fluoride release and release following refluoridation of three resin-modified glass-ionomer cements (Photac-Fil Applicap, Vitremer, and Fuji II LC) and a new polyacid-modified resin composite material (Dyract). After daily flouride release was measured for 8 days, specimens were refluoridated in 1,000-ppm solutions of fluoride ion for 10 minutes and fluoride release was measured for 5 days. Two further 5-day refluoridation-release periods were carried out. All materials released fluoride initially. Photac released the most; Dyract released the least. Initial release was greatest over the first few days. All materials released significantly more fluoride for 24 to 48 hours after refluoridation. Less fluoride was released with each successive refluoridation for the three glass-ionomer cements. The release from the Dyract compomer remained at a comparatively constant and significantly lower level following each refluoridation.

  2. Facile preparation of ion-imprinted composite film for selective electrochemical removal of nickel(II) ions.

    Science.gov (United States)

    Du, Xiao; Zhang, Hao; Hao, Xiaogang; Guan, Guoqing; Abudula, Abuliti

    2014-06-25

    A facile unipolar pulse electropolymerization (UPEP) technique is successfully applied for the preparation of ion-imprinted composite film composed of ferricyanide-embedded conductive polypyrrole (FCN/PPy) for the selective electrochemical removal of heavy metal ions from wastewater. The imprinted heavy metal ions are found to be easily removed in situ from the growing film only by tactfully applying potential oscillation due to the unstable coordination of FCN to the imprinted ions. The obtained Ni(2+) ion-imprinted FCN/PPy composite film shows fast uptake/release ability for the removal of Ni(2+) ions from aqueous solution, and the adsorption equilibrium time is less than 50 s. The ion exchange capacity reaches 1.298 mmol g(-1) and retains 93.5% of its initial value even after 1000 uptake/release cycles. Separation factors of 6.3, 5.6, and 6.2 for Ni(2+)/Ca(2+), Ni(2+)/K(+), and Ni(2+)/Na(+), respectively, are obtained. These characteristics are attributed to the high identification capability of the ion-imprinted composite film for the target ions and the dual driving forces resulting from both PPy and FCN during the redox process. It is expected that the present method can be used for simple preparation of other ion-imprinted composite films for the separation and recovery of target heavy metal ions as well.

  3. Bioactivity of Sodium Free Fluoride Containing Glasses and Glass-Ceramics

    Directory of Open Access Journals (Sweden)

    Xiaojing Chen

    2014-07-01

    Full Text Available The bioactivity of a series of fluoride-containing sodium-free calcium and strontium phosphosilicate glasses has been tested in vitro. Glasses with high fluoride content were partially crystallised to apatite and other fluoride-containing phases. The bioactivity study was carried out in Tris and SBF buffers, and apatite formation was monitored by XRD, FTIR and solid state NMR. Ion release in solutions has been measured using ICP-OES and fluoride-ion selective electrode. The results show that glasses with low amounts of fluoride that were initially amorphous degraded rapidly in Tris buffer and formed apatite as early as 3 h after immersion. The apatite was identified as fluorapatite by 19F MAS-NMR after 6 h of immersion. Glass degradation and apatite formation was significantly slower in SBF solution compared to Tris. On immersion of the partially crystallised glasses, the fraction of apatite increased at 3 h compared to the amount of apatite prior to the treatment. Thus, partial crystallisation of the glasses has not affected bioactivity significantly. Fast dissolution of the amorphous phase was also indicated. There was no difference in kinetics between Tris and SBF studies when the glass was partially crystallised to apatite before immersion. Two different mechanisms of apatite formation for amorphous or partially crystallised glasses are discussed.

  4. Association between Urine Fluoride and Dental Fluorosis as a Toxicity Factor in a Rural Community in the State of San Luis Potosi

    Directory of Open Access Journals (Sweden)

    Lizet Jarquín-Yañez

    2015-01-01

    Full Text Available Objective. The aim of this study is to investigate urine fluoride concentration as a toxicity factor in a rural community in the state of San Luis Potosi, Mexico. Materials and Methods. A sample of 111 children exposed to high concentrations of fluoride in drinking water (4.13 mg/L was evaluated. Fluoride exposure was determined by measuring urine fluoride concentration using the potentiometric method with an ion selective electrode. The diagnosis of dental fluorosis was performed by clinical examination, and the severity of damage was determined using Dean’s index and the Thylstrup-Fejerskov (TF index. Results. The range of exposure in the study population, evaluated through the fluoride content in urine, was 1.1 to 5.9 mg/L, with a mean of 3.14 ± 1.09 mg/L. Dental fluorosis was present in all subjects, of which 95% had severe cases. Higher urine fluoride levels and greater degrees of severity occurred in older children. Conclusions. The results show that dental fluorosis was determined by the presence of fluoride exposure finding a high positive correlation between the severity of fluorosis and urine fluoride concentration and the years of exposure suggested a cumulative effect.

  5. Association between Urine Fluoride and Dental Fluorosis as a Toxicity Factor in a Rural Community in the State of San Luis Potosi

    Science.gov (United States)

    Jarquín-Yañez, Lizet; Mejía-Saavedra, José de Jesús; Molina-Frechero, Nelly; Gaona, Enrique; Rocha-Amador, Diana Olivia; López-Guzmán, Olga Dania; Bologna-Molina, Ronell

    2015-01-01

    Objective. The aim of this study is to investigate urine fluoride concentration as a toxicity factor in a rural community in the state of San Luis Potosi, Mexico. Materials and Methods. A sample of 111 children exposed to high concentrations of fluoride in drinking water (4.13 mg/L) was evaluated. Fluoride exposure was determined by measuring urine fluoride concentration using the potentiometric method with an ion selective electrode. The diagnosis of dental fluorosis was performed by clinical examination, and the severity of damage was determined using Dean's index and the Thylstrup-Fejerskov (TF) index. Results. The range of exposure in the study population, evaluated through the fluoride content in urine, was 1.1 to 5.9 mg/L, with a mean of 3.14 ± 1.09 mg/L. Dental fluorosis was present in all subjects, of which 95% had severe cases. Higher urine fluoride levels and greater degrees of severity occurred in older children. Conclusions. The results show that dental fluorosis was determined by the presence of fluoride exposure finding a high positive correlation between the severity of fluorosis and urine fluoride concentration and the years of exposure suggested a cumulative effect. PMID:25789336

  6. Association between urine fluoride and dental fluorosis as a toxicity factor in a rural community in the state of San Luis Potosi.

    Science.gov (United States)

    Jarquín-Yañez, Lizet; de Jesús Mejía-Saavedra, José; Molina-Frechero, Nelly; Gaona, Enrique; Rocha-Amador, Diana Olivia; López-Guzmán, Olga Dania; Bologna-Molina, Ronell

    2015-01-01

    The aim of this study is to investigate urine fluoride concentration as a toxicity factor in a rural community in the state of San Luis Potosi, Mexico. A sample of 111 children exposed to high concentrations of fluoride in drinking water (4.13 mg/L) was evaluated. Fluoride exposure was determined by measuring urine fluoride concentration using the potentiometric method with an ion selective electrode. The diagnosis of dental fluorosis was performed by clinical examination, and the severity of damage was determined using Dean's index and the Thylstrup-Fejerskov (TF) index. The range of exposure in the study population, evaluated through the fluoride content in urine, was 1.1 to 5.9 mg/L, with a mean of 3.14±1.09 mg/L. Dental fluorosis was present in all subjects, of which 95% had severe cases. Higher urine fluoride levels and greater degrees of severity occurred in older children. The results show that dental fluorosis was determined by the presence of fluoride exposure finding a high positive correlation between the severity of fluorosis and urine fluoride concentration and the years of exposure suggested a cumulative effect.

  7. First state selective electron capture measurements with trapped highly charged ions

    NARCIS (Netherlands)

    Bliek, F.W.; Woestenenk, G.R.; Hoekstra, R.A.; Morgenstern, R.W.H.

    1997-01-01

    The first state selective electron capture cross section measurements at eV energies are reported for collisions between C4+ ions and H-2 molecules. The cross sections are measured in a crossed beam experiment by means of Photon Emission Spectroscopy. The ion beams are decelerated in an octopole ion

  8. A Novel Method for the Selective Determination of Silver (I) Ion

    Institute of Scientific and Technical Information of China (English)

    Jian Gong LIANG; Hai Yan XIE; Xin Ping AI; Zhi Ke HE; Dai Wen PANG

    2004-01-01

    Water-soluble CdSe quantum dots (QDs) capped by bovine serum albumin (BSA) is described as selective silver (I) ion probe based on their fluorescence (FL) quenched by silver ion at pH 5.7. The detection limit is 3×10-7 mol L-1 for silver ion. The interference was also investigated.

  9. Ion source parameters and hydrogen scrambling in the ECD of selectively deuterated peptides

    DEFF Research Database (Denmark)

    Duchateau, Magalie; Jørgensen, Thomas J. D.; Robine, Ophélie

    2014-01-01

    . In the present work, we investigate the occurrence of scrambling in the Apollo I electrospray ion source using ECD of selectively deuterium labeled peptides. The electrospray ion source settings leading to minimal scrambling were identified. Furthermore, an energy dependent loss of deuterium occurring in the ion...

  10. Site Selective Spectroscopy on Erbium Ions in Stoichiometric Lithium Tantalate

    Energy Technology Data Exchange (ETDEWEB)

    Miyahara, K; Toulouse, A; Woodward, N; Capek, P; Dierolf, V, E-mail: vod2@lehigh.ed [Physics Department Lehigh University, Bethlehem, PA 18015 (United States)

    2010-11-01

    Ferroelectric materials such as lithium niobate (LiNbO{sub 3}) and the isostructural lithium tantalate (LiTaO{sub 3}) play an important role in integrated optics since they allow the possibility to combine their favourable electro-optical, acousto-optical, and nonlinear properties with the ability to add additional functional groups by doping. Examples are rare earth ions that act as active centres for laser and optical amplifier applications. We present our sites-selective spectroscopic studies on Er{sup 3+} doped nearly stoichiometric LiTaO{sub 3} that include results about the assignment of excitation and emission peaks to different sites, symmetry properties of these sites, energy transfer among major sites, and up-conversion efficiencies. We compare the results in LiTiO{sub 3} with the corresponding ones in the much better studied LiNbO{sub 3} host and find that the type of centres and their spectral feature are very similar.

  11. A Novel Ion - selective Polymeric Membrane Sensor for Determining Thallium(I) With High Selectivity

    Science.gov (United States)

    Kassim, Anuar; Rezayi, Majid; Ahmadzadeh, Saeid; Rounaghi, Gholamhossein; Mohajeri, Masoomeh; Azah Yusof, Noor; Tee, Tan Wee; Yook Heng, Lee; Halim Abdullah, Abd

    2011-02-01

    Thallium is a toxic metal that introduced into the environment mainly as a waste from the production of zinc, cadmium, and lead and by combustion of coal. Thallium causes gastrointestinal irritation and nerve damage when people are exposed to it for relatively short period of time. For long term, thallium has the potential to cause the following effects: change in blood chemistry, damage to liver, kidney, intestinal and testicular tissue, and hair loss. In this work a membrane was prepared by use of 4'-nitrobenzo -18-crown-6 (4'NB18C6) as an ion carrier, polyvinylchloride (PVC) as a matrix, and diocthylphetalate (DOP) as a plasticizer for making an ion selective electrode for measurement of Tl+ cation in solutions. The amount of 4'-nitrobenzo-18C6 and polyvinylchloride were optimized in the preparation of the membrane. The response of the electrode was Nernstian within the concentration range 1.0 × 10-8 to 1.0 × 10-1M. This sensor displays a drift in Nernstian response for this cation with increasing the amount of ionophore and decreasing the amount of polyvinylchloride.The results of potentiometric measurements showed that, this electrode also responses to Cu2+ Ni2+ and Pb2+ cations, but the electrode has a wider dynamic range and a lower detection limit to Tl+ cation. The effects of various parameters such as pH, different cations interferences, effect of the amount of ionophore and polyvinylchloride and time on response of the coated ion selective electrode were investigated. Finally the constructed electrode was used in complexometric and precipitation titrations of Tl+ cation with EDTA and KBr, respectively. The response of the fabricated electrode at concentration range from 1.0 × 10-8 to 1.0 × 10-1M is linear with a Nernstian slope of 57.27 mV.

  12. [Epidemiological pattern of abnormal urinary fluoride rates in population with occupational fluoride exposure in Shanghai].

    Science.gov (United States)

    Gu, M H; Su, J; Liu, C H; Zhu, Y Q; Shen, H; Huang, Y H; Zhong, L; Zhang, M H; Li, Y H

    2017-01-10

    Objective: To investigate the epidemiological features of abnormal urinary fluoride rates in population with occupational exposure, and its relationships with age, work years and gender in Shanghai. Methods: A questionnaire survey was conducted respectively in 4 999 exposed workers and 283 non-exposed people during 2012-2015. Their urine samples were collected in plastic bottles and the fluoride ion selective electrode method was used for urinary fluoride level analysis. Logistic regression model was used to estimate associations between the abnormal rates and demographic/socioeconomic status of the study subjects. Results: In the past 4 years, the abnormal urinary fluoride rates (≥1.6 mg/L) in the population with occupational exposure was about 14.38%, it was about 1.43% in the control groups without occupational exposure. Their geometric mean of urinary fluoride content was 0.95 mg/L and 0.46 mg/L, respectively. The incidences of the abnormal rates in those aged ≥50 years and 34-39 years were 19.15% and 22.39%, respectively. The abnormal rate in males was 16.87%, much higher than that in females (6.85%). The abnormal rate had an upward trend along with the increased work years, especially in those with work years of ≥20 years. The abnormal rate was 23.28% in those with work years of ≥20 years and 13.29% in those with work years of fluoride rates was higher in male group, older age group and longer work year group, the odds ratio was 2.28, 1.10 and 1.13, respectively. Conclusions: Serious challenges exist in occupational health supervision. The relevant national standards should be updated as soon as possible. Males, those aged >50 years, and those with longer work years are the risk groups for intervention measures. More efforts are needed, such as strengthening the innovative application of health examination data and the equalization of basic public health service with comprehensive occupational health supervision programs among off-farm workers in the

  13. Mobility-resolved ion selection in uniform drift field ion mobility spectrometry/mass spectrometry: dynamic switching in structures for lossless ion manipulations.

    Science.gov (United States)

    Webb, Ian K; Garimella, Sandilya V B; Tolmachev, Aleksey V; Chen, Tsung-Chi; Zhang, Xinyu; Cox, Jonathan T; Norheim, Randolph V; Prost, Spencer A; LaMarche, Brian; Anderson, Gordon A; Ibrahim, Yehia M; Smith, Richard D

    2014-10-07

    A Structures for Lossless Ion Manipulations (SLIM) module that allows ion mobility separations and the switching of ions between alternative drift paths is described. The SLIM switch component has a "Tee" configuration and allows the efficient switching of ions between a linear path and a 90-degree bend. By controlling switching times, ions can be efficiently directed to an alternative channel as a function of their mobilities. In the initial evaluation the switch is used in a static mode and shown compatible with high performance ion mobility separations at 4 Torr. In the dynamic mode, we show that mobility-selected ions can be switched into the alternative channel, and that various ion species can be independently selected based on their mobilities for time-of-flight mass spectrometer (TOF MS) IMS detection and mass analysis. This development also provides the basis of, for example, the selection of specific mobilities for storage and accumulation, and the key component of modules for the assembly of SLIM devices enabling much more complex sequences of ion manipulations.

  14. Properties of Hydrated Alkali Metals Aimed at the Ion Channel Selectivity

    Institute of Scientific and Technical Information of China (English)

    AN Hai-Long; LIU Yu-Zhi; ZHANG Su-Hua; ZHAN Yong; ZHANG Hai-Lin

    2008-01-01

    The hydration structure properties of different alkali metal ions with eight water molecules and potassium ions with different numbers of water molecules are studied using the mixed density functional theory, B3LYP, with 6-311G basis set. The hydration structures are obtained from structure optimization and the optimum numbers of water molecules in the innermost hydration shell for the alkali metal ions are found. Some useful information about the ion channel selectivity is presented.

  15. Transport-limited water splitting at ion-selective interfaces during concentration polarization

    OpenAIRE

    Nielsen, Christoffer Peder; Bruus, Henrik

    2013-01-01

    We present an analytical model of salt- and water-ion transport across an ion-selective interface based on an assumption of local equilibrium of the water-dissociation reaction. The model yields current-voltage characteristics and curves of water-ion current versus salt-ion current, which are in qualitative agreement with experimental results published in the literature. The analytical results are furthermore in agreement with direct numerical simulations. As part of the analysis, we find app...

  16. Divalent Metal Ion Transport across Large Biological Ion Channels and Their Effect on Conductance and Selectivity

    Directory of Open Access Journals (Sweden)

    Elena García-Giménez

    2012-01-01

    Full Text Available Electrophysiological characterization of large protein channels, usually displaying multi-ionic transport and weak ion selectivity, is commonly performed at physiological conditions (moderate gradients of KCl solutions at decimolar concentrations buffered at neutral pH. We extend here the characterization of the OmpF porin, a wide channel of the outer membrane of E. coli, by studying the effect of salts of divalent cations on the transport properties of the channel. The regulation of divalent cations concentration is essential in cell metabolism and understanding their effects is of key importance, not only in the channels specifically designed to control their passage but also in other multiionic channels. In particular, in porin channels like OmpF, divalent cations modulate the efficiency of molecules having antimicrobial activity. Taking advantage of the fact that the OmpF channel atomic structure has been resolved both in water and in MgCl2 aqueous solutions, we analyze the single channel conductance and the channel selectivity inversion aiming to separate the role of the electrolyte itself, and the counterion accumulation induced by the protein channel charges and other factors (binding, steric effects, etc. that being of minor importance in salts of monovalent cations become crucial in the case of divalent cations.

  17. Geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples, and its possible relationship with the prevalence of enamel fluorosis in children in four municipalities of the department of Huila (Colombia).

    Science.gov (United States)

    Martignon, Stefania; Opazo-Gutiérrez, Mario Omar; Velásquez-Riaño, Möritz; Orjuela-Osorio, Iván Rodrigo; Avila, Viviana; Martinez-Mier, Esperanza Angeles; González-Carrera, María Clara; Ruiz-Carrizosa, Jaime Alberto; Silva-Hermida, Blanca Cecilia

    2017-06-01

    Fluoride is an element that affects teeth and bone formation in animals and humans. Though the use of systemic fluoride is an evidence-based caries preventive measure, excessive ingestion can impair tooth development, mainly the mineralization of tooth enamel, leading to a condition known as enamel fluorosis. In this study, we investigated the geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples in four endemic enamel fluorosis sentinel municipalities of the department of Huila, Colombia (Pitalito, Altamira, El Agrado and Rivera), and its possible relationship with the prevalence of enamel fluorosis in children. The concentration of fluoride in drinking water, table salt, active sediment, rock, and soil was evaluated by means of an ion selective electrode and the geochemical analyses were performed using X-ray fluorescence. Geochemical analysis revealed fluoride concentrations under 15 mg/kg in active sediment, rock and soil samples, not indicative of a significant delivery to the watersheds studied. The concentration of fluoride in table salt was found to be under the inferior limit (less than 180 μg/g) established by the Colombian regulations. Likewise, exposure doses for fluoride water intake did not exceed the recommended total dose for all ages from 6 months. Although the evidence does not point out at rocks, soils, fluoride-bearing minerals, fluoridated salt and water, the hypothesis of these elements as responsible of the current prevalence of enamel fluorosis cannot be discarded since, aqueducts might have undergone significant changes overtime.

  18. Electrolyte-gated organic field-effect transistor for selective reversible ion detection.

    Science.gov (United States)

    Schmoltner, Kerstin; Kofler, Johannes; Klug, Andreas; List-Kratochvil, Emil J W

    2013-12-17

    An ion-sensitive electrolyte-gated organic field-effect transistor for selective and reversible detection of sodium (Na(+) ) down to 10(-6) M is presented. The inherent low voltage - high current operation of these transistors in combination with a state-of-the-art ion-selective membrane proves to be a novel, versatile modular sensor platform.

  19. Synthesis of indolo[3,2-b]carbazole-based new colorimetric receptor for anions: A unique color change for fluoride ions

    Directory of Open Access Journals (Sweden)

    Ajit Kumar Mahapatra

    2010-02-01

    Full Text Available A novel indolocarbazole-based chemosensor 1 containing hydrogen bond donor moieties has been established as a selective colorimetric and fluorometric sensor for F− in CH3CN/H2O (4:1 v/v. Upon the addition of a series of tetrabutylammonium salts to receptor 1 in aqueous CH3CN, only when the counter ion was F− was a significant color change (from light violet to dark orange observed.

  20. Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon

    Energy Technology Data Exchange (ETDEWEB)

    Soto, Fernando A. [Department of Chemical Engineering, Texas A& M University, College Station TX 77843-3122 USA; Yan, Pengfei [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Engelhard, Mark H. [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Marzouk, Asma [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825 Doha Qatar; Wang, Chongmin [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Xu, Guiliang [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Chen, Zonghai [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Amine, Khalil [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Liu, Jun [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Sprenkle, Vincent L. [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; El-Mellouhi, Fedwa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825 Doha Qatar; Balbuena, Perla B. [Department of Chemical Engineering, Texas A& M University, College Station TX 77843-3122 USA; Li, Xiaolin [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA

    2017-03-07

    Solid-electrolyte interphase (SEI) with controllable properties are highly desirable to improve battery performance. In this paper, we use a combined experimental and simulation approach to study the SEI formation on hard carbon in Li and Na-ion batteries. We show that with proper additives, stable SEI can be formed on hard carbon by pre-cycling the electrode materials in Li or Na-ion electrolyte. Detailed mechanistic studies suggest that the ion transport in the SEI layer is kinetically controlled and can be tuned by the applied voltage. Selective Na and Li-ion SEI membranes are produced using the Na or Li-ion based electrolytes respectively. The large Na ion SEI allows easy transport of Li ions, while the small Li ion SEI shuts off the Na-ion transport. Na-ion storage can be manipulated by tuning the SEI with film-forming electrolyte additives or preforming a SEI on the electrodes’ surface. The Na specific capacity can be controlled to <25 mAh/g, ~1/10 of the normal capacity (250 mAh/g). Unusual selective/preferential transport of Li-ion is demonstrated by preforming a SEI on the electrode’s surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion selective conductors using electrochemical approaches in the future.

  1. Selective inhibition of ammonium oxidation and nitrification-linked N2O formation by methyl fluoride and dimethyl ether

    Science.gov (United States)

    Miller, L.G.; Coutlakis, M.D.; Oremland, R.S.; Ward, B.B.

    1993-01-01

    Methyl fluoride (CH3F) and dimethyl ether (DME) inhibited nitrification in washed-cell suspensions of Nitrosomonas europaea and in a variety of oxygenated soils and sediments. Headspace additions of CH3F (10% [vol/vol]) and DME (25% [vol/vol]) fully inhibited NO2- and N2O production from NH4+ in incubations of N. europaea, while lower concentrations of these gases resulted in partial inhibition. Oxidation of hydroxylamine (NH2OH) by N. europaea and oxidation of NO2- by a Nitrobacter sp. were unaffected by CH3F or DME. In nitrifying soils, CH3F and DME inhibited N2O production. In field experiments with surface flux chambers and intact cores, CH3F reduced the release of N2O from soils to the atmosphere by 20- to 30-fold. Inhibition by CH3F also resulted in decreased NO3- + NO2- levels and increased NH4+ levels in soils. CH3F did not affect patterns of dissimilatory nitrate reduction to ammonia in cell suspensions of a nitrate- respiring bacterium, nor did it affect N2O metabolism in denitrifying soils. CH3F and DME will be useful in discriminating N2O production via nitrification and denitrification when both processes occur and in decoupling these processes by blocking NO2- and NO3- production.

  2. Occupational fluoride exposure. [Review

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, H.C. (Univ. of California, San Francisco); Smith, F.A.

    1977-01-01

    Effects of airborne fluoride on industrial health are discussed with regard to acute and chronic effects. Injuries to lungs and skin from acute exposures are described. Chronic effects are discussed with regard to industrial sources of fluoride and air concentrations vs. urinary concentrations of fluoride. An extensive literature review is presented in the form of a table showing responses in man exposed to industrial airborne fluorides. Osteosclerosis is discussed with regard to the fluoride air standard, bone fluoride, and air fluoride concentrations. Occupational exposures to fluoride are also discussed with regard to arthritis, shortness of breath, asthma, upper respiratory infections, chronic respiratory disease, effects on kidneys, effects on pregnancy, and indices of fluoride intoxication. A table is presented showing references to studies on responses in neighborhood residents exposed to fluoride emissions. (HLW)

  3. High-capacity lithium-ion battery conversion cathodes based on iron fluoride nanowires and insights into the conversion mechanism.

    Science.gov (United States)

    Li, Linsen; Meng, Fei; Jin, Song

    2012-11-14

    The increasing demands from large-scale energy applications call for the development of lithium-ion battery (LIB) electrode materials with high energy density. Earth abundant conversion cathode material iron trifluoride (FeF(3)) has a high theoretical capacity (712 mAh g(-1)) and the potential to double the energy density of the current cathode material based on lithium cobalt oxide. Such promise has not been fulfilled due to the nonoptimal material properties and poor kinetics of the electrochemical conversion reactions. Here, we report for the first time a high-capacity LIB cathode that is based on networks of FeF(3) nanowires (NWs) made via an inexpensive and scalable synthesis. The FeF(3) NW cathode yielded a discharge capacity as high as 543 mAh g(-1) at the first cycle and retained a capacity of 223 mAh g(-1) after 50 cycles at room temperature under the current of 50 mA g(-1). Moreover, high-resolution transmission electron microscopy revealed the existence of continuous networks of Fe in the lithiated FeF(3) NWs after discharging, which is likely an important factor for the observed improved electrochemical performance. The loss of active material (FeF(3)) caused by the increasingly ineffective reconversion process during charging was found to be a major factor responsible for the capacity loss upon cycling. With the advantages of low cost, large quantity, and ease of processing, these FeF(3) NWs are not only promising battery cathode materials but also provide a convenient platform for fundamental studies and further improving conversion cathodes in general.

  4. Determination of bromide, chloride, fluoride, nitrate and sulphate by ion chromatography: comparisons of methodologies for rainfall, cloud water and river waters at the Plynlimon catchments of mid-Wales

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available The results of determination of bromide, chloride, fluoride, nitrate and sulphate using ion chromatography (IC are compared with those obtained by colorimetric and inductively coupled plasma optical emission spectroscopy (ICPOES for rainfall, cloud water and stream waters in the Plynlimon experimental catchments of mid-Wales. For bromide, the concentrations determined by IC are lower than those for the colorimetric method used; the colorimetric method probably determined bromide plus organo-bromine compounds. It is suggested that the values determined by the colorimetric method be termed dissolved labile bromine (DLBr. The study shows that sulphate is the overriding form of sulphur in the waters. For chloride and nitrate, measurements by both methods approach a 1:1 relationship that is barely statistically significantly different from unity. For fluoride, the IC method gives lower values than the colorimetric, especially for the stream waters. However, the colorimetric method determines total fluorine so that a difference is to be expected (for example, fluoride strongly complexes with aluminium that is present, especially in the streamwater.

  5. State selective capture by highly charged Xe ions

    NARCIS (Netherlands)

    Hasan, V. G.; Knoop, S.; Morgenstern, R.; Hoekstra, R.; McCullough, RW; Currell, FJ; Greenwood, J; Gribakin, G; Scott, MP

    2007-01-01

    Single-electron capture in collisions of highly charged ions Xe18+ and Xe24+ with Na atoms is investigated by measuring the momenta of the Na recoil ions. The Q-value spectrum in Xe18+ + Na collisions shows capture into lower n states compared with Classical over-barrier model (CBM) calculations.

  6. Effects of fluoridation of porcine hydroxyapatite on osteoblastic activity of human MG63 cells

    Science.gov (United States)

    Li, Zhipeng; Huang, Baoxin; Mai, Sui; Wu, Xiayi; Zhang, Hanqing; Qiao, Wei; Luo, Xin; Chen, Zhuofan

    2015-06-01

    Biological hydroxyapatite, derived from animal bones, is the most widely used bone substitute in orthopedic and dental treatments. Fluorine is the trace element involved in bone remodeling and has been confirmed to promote osteogenesis when administered at the appropriate dose. To take advantage of this knowledge, fluorinated porcine hydroxyapatite (FPHA) incorporating increasing levels of fluoride was derived from cancellous porcine bone through straightforward chemical and thermal treatments. Physiochemical characteristics, including crystalline phases, functional groups and dissolution behavior, were investigated on this novel FPHA. Human osteoblast-like MG63 cells were cultured on the FPHA to examine cell attachment, cytoskeleton, proliferation and osteoblastic differentiation for in vitro cellular evaluation. Results suggest that fluoride ions released from the FPHA play a significant role in stimulating osteoblastic activity in vitro, and appropriate level of fluoridation (1.5 to 3.1 atomic percents of fluorine) for the FPHA could be selected with high potential for use as a bone substitute.

  7. Evaluation of Effect of Brushite-Calcite and Two Indigenous Herbs in Removal of Fluoride from Water

    Science.gov (United States)

    Naveenkumar, Puvvadi Gopalakrishna; Prashant, Gouder Manjunath; Sakeenabi, Basha; Allamaprabhu; Vijetha, Kothyala

    2016-01-01

    Introduction The acceptable concentration of fluoride in drinking water is 1.5mg/l. Excess fluoride in drinking water causes fluorosis. Fluorosis is an important public health problem in India. Several treatment technologies suggested in the past for removing excess fluoride generated and causes various chemical byproductswhich are hazardous to public. In recent years, there has been a resurgence of interest to use natural materials due to cost and associated health and environmental concerns of synthetic organic polymers and inorganic chemicals. Aim The aim of this study was to evaluate and compare the defluoridating capability of the brushite-calcite with that of two indigenous herbs, tulsi and wheat grass. Materials and Methods One gram of brushite-calcite combination, tulsi and wheat grass were separately added to 10 containers, each containing 1.0 l of prepared distilled water with a fluoride concentration of 5ppm and naturally fluoridated water at 2ppm. Half of the samples were boiled for one minute in a domestic electric kettle for one minute and allowed to cool. The remaining half of the samples was left un-boiled. Fluoride concentration in all the samples was assessed at the end of 30 minutes and 24 hours using fluoride ion selective electrode method. Data was analyzed using unpaired t-test and one-way ANOVA. Results For water with 2ppm and 5ppm fluoride, brushite-calcite had shown highest de-fluoridation capacity (p=0.001) at the end of both 30 minutes and 24 hours in boiled samples whereas tulsi (p=0.001) was most effective in un-boiled samples. Conclusion The results of the study suggest that tulsi can be used for domestic water defluoridation as it is economic, safe and effective. PMID:27504417

  8. In Vitro Comparison of the Effects of Diode Laser and CO2 Laser on Topical Fluoride Uptake in Primary Teeth

    Directory of Open Access Journals (Sweden)

    Zahra Bahrololoomi

    2016-04-01

    Full Text Available Objectives: Fluoride therapy is important for control and prevention of dental caries. Laser irradiation can increase fluoride uptake especially when combined with topical fluoride application. The objective of this study was to compare the effects of CO2 and diode lasers on enamel fluoride uptake in primary teeth.Materials and Methods: Forty human primary molars were randomly assigned to four groups (n=10. The roots were removed and the crowns were sectioned mesiodistally into buccal and lingual halves as the experimental and control groups. All samples were treated with 5% sodium fluoride (NaF varnish. The experimental samples in the four groups were irradiated with 5 or 7W diode or 1 or 2W CO2 laser for 15 seconds and were compared with the controls in terms of fluoride uptake, which was determined using an ion selective electrode after acid dissolution of the specimens. Data were analyzed by SPSS version 16 using ANOVA treating the control measurements as covariates.Results: The estimated amount of fluoride uptake was 59.5± 16.31 ppm, 66.5± 14.9 ppm, 78.6± 12.43 ppm and 90.4± 11.51 ppm for 5W and 7 W diode and 1W and 2 W CO2 lasers, respectively, which were significantly greater than the values in the conventional topical fluoridation group (P<0.005. There were no significant differences between 7W diode laser and 1W CO2 laser, 5W and 7W diode laser, or 1W and 2W CO2 laser in this regard.Conclusion: The results showed that enamel surface irradiation by CO2 and diode lasers increases the fluoride uptake.

  9. Relationship between water, urine and serum fluoride and fluorosis in school children of Jhajjar District, Haryana, India

    Science.gov (United States)

    Kumar, Sunil; Lata, Suman; Yadav, Jyoti; Yadav, J. P.

    2016-10-01

    The present study was undertaken to determine the relationship between fluoride in water, urine and serum and dental fluorosis. The fluoride level in water and urine were measured spectrophotometrically by using acid zirconyl and SPADNS reagents, while the fluoride level in serum was determined by ion selective electrode meter. Dental fluorosis survey was conducted with the help of Performa prescribed by Rajiv Gandhi Drinking Water Mission and the use of Tooth Surface Index for Fluorosis. Mean fluoride values in water samples of Jhajjar City and Dadanpur and Dariyapur villages of Jhajjar District were measured to be 2.17 (range from 1.92 to 2.60 mg/L), 2.81 (range from 2.53 to 3.14 mg/L) and 2.22 mg/L (range from 1.63 to 3.33 mg/L), respectively. The mean fluoride values in the urine samples of children were found to be 1.51 (range from 0.05 to 2.64 mg/L), 1.71 (range from 0.69 to 2.80 mg/L) and 1.45 mg/L (range from 0.31 to 2.50 mg/L) at Jhajjar City and Dadanpur and Dariyapur sites, respectively. Serum fluoride was detected in the blood samples of children, who have high urinary fluoride at these three sites. The mean serum fluoride level was reported to be 0.15, 0.34 and 0.17 mg/L, respectively. A total of 842 children were also analyzed for dental fluorosis. The mean values of fluorosis-affected children in Jhajjar, Dadanpur and Dariyapur were 51.90, 94.63 and 36.84 %, respectively. A significantly positive correlation between water, urine, serum fluoride concentration and fluorosis was seen.

  10. Distribution of fluoride and calcium in plaque biofilms after the use of conventional and low-fluoride dentifrices.

    Science.gov (United States)

    Pessan, Juliano Pelim; Pinto Alves, Karina Mirela Ribeiro; Italiani, Flávia de Moraes; Ramires, Irene; Lauris, José Roberto Pereira; Whitford, Gary Milton; Toumba, Kyriacos Jack; Robinson, Colin; Buzalaf, Marilia Afonso Rabelo

    2014-07-01

    The distribution of fluoride and calcium in plaque after the use of fluoride dentifrices has not yet been determined. To evaluate fluoride and calcium distribution in sections of biofilms generated in situ after the use of conventional and low-fluoride dentifrices. Children (n = 11, 8–10 years old) brushed with placebo (fluoride-free), low-fluoride (513 mgF/kg), and conventional (1072 mgF/kg) dentifrices twice daily for 1 week, following a double-blind, cross-over protocol. Biofilms were generated using Leeds in situ devices, which were collected 1 and 12 h after brushing, and sectioned through their depth. Sections were grouped (10 x 5 μm) for fluoride and calcium analysis. Sections 4 lm thick were used for image analysis and determination of biomass fraction. Results were analysed by ANOVA, Tukey’s test, and linear regression analysis (P dentifrices tested, and these ions were directly correlated throughout most of biofilm’s sections. Results for conventional dentifrice were significantly higher than for the placebo, but did not differ from those for the low-fluoride dentifrice. The use of a low-fluoride dentifrice did not promote a higher fluoride uptake in inner biofilms’ sections, as hypothesized. As plaque fluoride was significantly elevated only after the use of the conventional dentifrice, the recommendation of low-fluoride formulations should be done with caution, considering both risks and benefits.

  11. Turn-On Fluorescent Chemosensor for Fluoride Based on Pyreneamide Derivative

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Nam Joong; Hong, Sung Won; Hong, Ju Hyun; Jeong, Ju Mi; Nam, Kye Chun [Seoul National University, Seoul (Korea, Republic of)

    2012-01-15

    A new chemosensor with pyreneamide derivative of bipyridine is synthesized. In the free ligand, pyreneamide derivative has nearly no fluorescence in acetonitrile solution. However, in the presence of fluoride ion, a 'turn-on' fluorescence was observed. Simultaneously, the colorless ligand solution became markedly orange when fluoride ion was added to pyreneamide derivative in acetonitrile. This phenomenon suggest that the PET (photoinduced electron transfer) between anion electron and pyrene unit was changed the π-π interaction between bipyridine and pyrene that was modified structure by deprotonation. On account of the important roles of anion in biological, clinical, environmental, catalysis, and chemical processes, the selective and efficient recognition of anion is an area of growing interest in supramolecular chemistry. In particular, the studies of chemosensors toward F{sup -} anion are quite intriguing because of its beneficial effects in human physiology. Also, fluoride is interest due to its established role in dental care and osteoporosis. However, an excess of fluoride ion can lead to fluorosis. Therefore, the development of reliable sensors for F{sup -} is needed for environment and human health care. Color changes that can be detected by the naked eye are widely used as signals for events owing to the inexpensive equipment required or no equipment at all.

  12. Fluoride-containing bioactive glasses: Glass design, structure, bioactivity, cellular interactions, and recent developments.

    Science.gov (United States)

    Shah, Furqan A

    2016-01-01

    Bioactive glasses (BGs) are known to bond to both hard and soft tissues. Upon exposure to an aqueous environment, BG undergoes ion exchange, hydrolysis, selective dissolution and precipitation of an apatite layer on their surface, which elicits an interfacial biological response resulting in bioactive fixation, inhibiting further dissolution of the glass, and preventing complete resorption of the material. Fluorine is considered one of the most effective in-vivo bone anabolic factors. In low concentrations, fluoride ions (F(-)) increase bone mass and mineral density, improve the resistance of the apatite structure to acid attack, and have well documented antibacterial properties. F(-) ions may be incorporated into the glass in the form of calcium fluoride (CaF2) either by part-substitution of network modifier oxides, or by maintaining the ratios of the other constituents relatively constant. Fluoride-containing bioactive glasses (FBGs) enhance and control osteoblast proliferation, differentiation and mineralisation. And with their ability to release fluoride locally, FBGs make interesting candidates for various clinical applications, dentinal tubule occlusion in the treatment of dentin hypersensitivity. This paper reviews the chemistry of FBGs and the influence of F(-) incorporation on the thermal properties, bioactivity, and cytotoxicity; and novel glass compositions for improved mechanical properties, processing, and bioactive potential. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Aptamer selection for fishing of palladium ion using graphene oxide-adsorbed nanoparticles.

    Science.gov (United States)

    Cho, Yea Seul; Lee, Eun Jeong; Lee, Gwan-Ho; Hah, Sang Soo

    2015-12-01

    A new aptamer selection method using graphene oxide (GO)-adsorbed nanoparticles (GO-adsorbed NPs) was employed for specific fishing of palladium ion. High affinity ssDNA aptamers were isolated through 13 rounds of selection and the capacity of the selected DNA aptamers for palladium ion uptake was measured, clarifying that DNA01 exhibits the highest affinity to palladium ion with a dissociation constant (Kd) of 4.60±1.17 μM. In addition, binding ability of DNA01 to palladium ion was verified against other metal ions, such as Li(+), Cs(+), Mg(2+), and Pt(2+). Results of the present study suggest that future modification of DNA01 may improve palladium ion-binding ability, leading to economic recovery of palladium from water solution.

  14. Zirconium fluoride glass - Surface crystals formed by reaction with water

    Science.gov (United States)

    Doremus, R. H.; Bansal, N. P.; Bradner, T.; Murphy, D.

    1984-01-01

    The hydrated surfaces of a zirconium barium fluoride glass, which has potential for application in optical fibers and other optical elements, were observed by scanning electron microscopy. Crystalline zirconium fluoride was identified by analysis of X-ray diffraction patterns of the surface crystals and found to be the main constituent of the surface material. It was also found that hydrated zirconium fluorides form only in highly acidic fluoride solutions. It is possible that the zirconium fluoride crystals form directly on the glass surface as a result of its depletion of other ions. The solubility of zirconium fluoride is suggested to be probably much lower than that of barium fluoride (0.16 g/100 cu cm at 18 C). Dissolution was determined to be the predominant process in the initial stages of the reaction of the glass with water. Penetration of water into the glass has little effect.

  15. FLUORIDE CONTENT OF COMMERCIALLY AVAILABLE SOY MILK PRODUCTS IN THAILAND.

    Science.gov (United States)

    Rirattanapong, Opas; Rirattanapong, Praphasri

    2016-01-01

    Abstract. In Thailand, the consumption of soy milk products is common but there is limited data about their fluoride content. The purpose of this study was to es- timate the fluoride content of soy milk products available in Thailand. Fluoride content was determined for 76 brands of soy milk using a F-ion-specific electrode. The fluoride concentrations ranged from 0.01 to 3.78 μg/ml. The fluoride content was not related to sugar content, soy bean content or the sterilization process. Among 3 brands of soy milk containing tea powder extract, the fluoride content was high (1.25 to 3.78 μg/ml). Most brands of soy milk tested in our study had fluoride content below the optimal daily intake but brands containing tea powder extract if consumed by children may increase their risk for fluorosis.

  16. Adverse effects of fluoride towards thyroid hormone metabolism

    Directory of Open Access Journals (Sweden)

    Enggar Abdullah Idris MZ

    2008-03-01

    Full Text Available An easily ionized fluoride compound like Sodium Fluoride (NaF has been used thus far as a dental caries prevention substance. However, fluoride ions also have a negative effect because it is very toxic. Several types of research on the effect of fluoride on guinea pigs and human beings indicate the presence synthesis obstruction of T3 and T4 that causes declined production, known as hypothyroidism. Hypothyroidism condition may obstruct tissue growth process and metabolism so as to impact various body organ systems. Preventive efforts against hypothyroidism caused by fluoride include avoiding diffusible fluoride compound intake, like NaF, in a long run systemic use, whereas efforts to overcome fluoride intoxication include consuming food that is rich in calcium, vitamin D, and antioxidant.

  17. Infrared spectroscopy of molecular ions in selected rotational and spin-orbit states

    Science.gov (United States)

    Jacovella, U.; Agner, J. A.; Schmutz, H.; Deiglmayr, J.; Merkt, F.

    2016-07-01

    First results are presented obtained with an experimental setup developed to record IR spectra of rotationally state-selected ions. The method we use is a state-selective version of a method developed by Schlemmer et al. [Int. J. Mass Spectrom. 185, 589 (1999); J. Chem. Phys. 117, 2068 (2002)] to record IR spectra of ions. Ions are produced in specific rotational levels using mass-analyzed-threshold-ionization spectroscopy. The state-selected ions generated by pulsed-field ionization of Rydberg states of high principal quantum number (n ≈ 200) are extracted toward an octupole ion guide containing a neutral target gas. Prior to entering the octupole, the ions are excited by an IR laser. The target gas is chosen so that only excited ions react to form product ions. These product ions are detected mass selectively as a function of the IR laser wavenumber. To illustrate this method, we present IR spectra of C 2 H2 + in selected rotational levels of the 2Πu,3/2 and 2Πu,1/2 spin-orbit components of the vibronic ground state.

  18. Surface ion-imprinted amino-functionalized cellulosic cotton fibers for selective extraction of Cu(II) ions.

    Science.gov (United States)

    Monier, M; Ibrahim, Amr A; Metwally, M M; Badawy, D S

    2015-11-01

    Surface ion-imprinted amino-functionalized cellulosic fibers (Cu-ABZ) were manufactured for efficient selective adsorption of Cu(2+) ions. The chemical modification steps had been characterized utilizing elemental analysis; Fourier transforms infrared (FTIR) along with wide angle X-ray diffraction (XRD) spectroscopy. Also, the morphological structure of the ion-imprinted and the non-imprinted (NI-ABZ) fibers were visualized and compared with that of the native cotton fibers using scanning electron microscope (SEM). In addition, the coordination mode by which the Cu(2+) ions bonded to the active sites were examined by both FTIR and X-ray photo electron spectra (XPS). Both Cu-ABZ and NI-ABZ were implemented in batch experiments for optimizing the conditions by which the Cu(2+) ions can be selectively removal from aqueous medium and pH 5 was the optimum for the metal ion extraction. Moreover, the kinetics and isotherm studies revealed that the adsorption data fitted with pseudo-second-order kinetic and Langmuir models with estimated maximum adsorption capacity 93.6mg/g. Also, the reusability studies indicated that the prepared ion-imprinted adsorbent maintains more than 95% of its original activity after fifth generation cycle.

  19. An ion selectivity filter in the extracellular domain of Cys-loop receptors reveals determinants for ion conductance.

    Science.gov (United States)

    Hansen, Scott B; Wang, Hai-Long; Taylor, Palmer; Sine, Steven M

    2008-12-26

    Neurotransmitter binding to Cys-loop receptors promotes a prodigious transmembrane flux of several million ions/s, but to date, structural determinants of ion flux have been identified flanking the membrane-spanning region. Using x-ray crystallography, sequence analysis, and single-channel recording, we identified a novel determinant of ion conductance near the point of entry of permeant ions. Co-crystallization of acetylcholine-binding protein with sulfate anions revealed coordination of SO4(2-) with a ring of lysines at a position equivalent to 24 A above the lipid membrane in homologous Cys-loop receptors. Analysis of multiple sequence alignments revealed that residues equivalent to the ring of lysines are negatively charged in cation-selective receptors but are positively charged in anion-selective receptors. Charge reversal of side chains at homologous positions in the nicotinic receptor from the motor end plate decreases unitary conductance up to 80%. Selectivity filters stemming from transmembrane alpha-helices have similar pore diameters and compositions of amino acids. These findings establish that when the channel opens under a physiological electrochemical gradient, permeant ions are initially stabilized within the extracellular vestibule of Cys-loop receptors, and this stabilization is a major determinant of ion conductance.

  20. Naphthatimide as Highly Selective Fluorescent Sensor for Ag+ Ions

    Institute of Scientific and Technical Information of China (English)

    XU,Sheng; LI,Wei; CHEN,Kong-Chang

    2007-01-01

    The naphthalimide derivative NA1 was synthesized, which consists of a bis(2-(ethylthio)ethyl)amine group binding cations and naphthalimide unit as chromogenic and fluorogenic signaling subunit. Absorption and emission spectra and the effect of polarity of solvents and pH values were studied. The photo-induced electron transfer (PET) occurred from the donor of bis(2-(ethylthio)ethyl)amine group to the naphthalimide fluorophore. The present study demonstrates that NA1 is a viable candidate as a fluorescent receptor for a new Ag+ ion sensor. This silver ion chemosensor can discriminate Ag+ ion well among heavy metal ions by an enhancement of the fluorescence intensity in ethanol-water (1:9, V:V). And NA1 is also a pH-sensor because the fluorescence of the compound varies with the pH values.

  1. Protein scaffolds for selective enrichment of metal ions

    Energy Technology Data Exchange (ETDEWEB)

    He, Chuan; Zhou, Lu; Bosscher, Michael

    2016-02-09

    Polypeptides comprising high affinity for the uranyl ion are provided. Methods for binding uranyl using such proteins are likewise provided and can be used, for example, in methods for uranium purification or removal.

  2. Vibrational excitons in ionophores: Experimental probes for quantum coherence-assisted ion transport and selectivity in ion channels

    CERN Document Server

    Ganim, Ziad; Vaziri, Alipasha

    2011-01-01

    Despite a large body of work, the exact molecular details underlying ion-selectivity and transport in the potassium channel have not been fully laid to rest. One major reason has been the lack of experimental methods that can probe these mechanisms dynamically on their biologically relevant time scales. Recently it was suggested that quantum coherence and its interplay with thermal vibration might be involved in mediating ion-selectivity and transport. In this work we present an experimental strategy for using time resolved infrared spectroscopy to investigate these effects. We show the feasibility by demonstrating the IR absorption and Raman spectroscopic signatures of potassium binding model molecules that mimic the transient interactions of potassium with binding sites of the selectivity filter during ion conduction. In addition to guide our experiments on the real system we have performed molecular dynamic-based simulations of the FTIR and 2DIR spectra of the entire KcsA complex, which is the largest comp...

  3. Influence of Ionic Liquids on the Selectivity of Ion Exchange-Based Polymer Membrane Sensing Layers.

    Science.gov (United States)

    Mendecki, Lukasz; Callan, Nicole; Ahern, Meghan; Schazmann, Benjamin; Radu, Aleksandar

    2016-07-16

    The applicability of ion exchange membranes is mainly defined by their permselectivity towards specific ions. For instance, the needed selectivity can be sought by modifying some of the components required for the preparation of such membranes. In this study, a new class of materials -trihexyl(tetradecyl)phosphonium based ionic liquids (ILs) were used to modify the properties of ion exchange membranes. We determined selectivity coefficients for iodide as model ion utilizing six phosphonium-based ILs and compared the selectivity with two classical plasticizers. The dielectric properties of membranes plasticized with ionic liquids and their response characteristics towards ten different anions were investigated using potentiometric and impedance measurements. In this large set of data, deviations of obtained selectivity coefficients from the well-established Hofmeister series were observed on many occasions thus indicating a multitude of applications for these ion-exchanging systems.

  4. A Novel Ion - selective Polymeric Membrane Sensor for Determining Thallium(I) With High Selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Kassim, Anuar; Rezayi, Majid; Ahmadzadeh, Saeid; Yusof, Noor Azah; Tee, Tan Wee; Abdullah, Abd Halim [Department of Chemistry Faculty of Science, Universiti Putra Malaysia 43400 Serdang, Selangor (Malaysia); Rounaghi, Gholamhossein; Mohajeri, Masoomeh [Department of Chemistry, Factuality of Sciences, Islamic Azad University of Mashhad, Mashhad (Iran, Islamic Republic of); Heng, Lee Yook, E-mail: anuar@science.upm.edu.my [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E. (Malaysia)

    2011-02-15

    Thallium is a toxic metal that introduced into the environment mainly as a waste from the production of zinc, cadmium, and lead and by combustion of coal. Thallium causes gastrointestinal irritation and nerve damage when people are exposed to it for relatively short period of time. For long term, thallium has the potential to cause the following effects: change in blood chemistry, damage to liver, kidney, intestinal and testicular tissue, and hair loss. In this work a membrane was prepared by use of 4'-nitrobenzo -18-crown-6 (4'NB18C6) as an ion carrier, polyvinylchloride (PVC) as a matrix, and diocthylphetalate (DOP) as a plasticizer for making an ion selective electrode for measurement of Tl{sup +} cation in solutions. The amount of 4'-nitrobenzo-18C6 and polyvinylchloride were optimized in the preparation of the membrane. The response of the electrode was Nernstian within the concentration range 1.0 x 10{sup -8} to 1.0 x 10{sup -1}M. This sensor displays a drift in Nernstian response for this cation with increasing the amount of ionophore and decreasing the amount of polyvinylchloride.The results of potentiometric measurements showed that, this electrode also responses to Cu{sup 2+} Ni{sup 2+} and Pb{sup 2+} cations, but the electrode has a wider dynamic range and a lower detection limit to Tl{sup +} cation. The effects of various parameters such as pH, different cations interferences, effect of the amount of ionophore and polyvinylchloride and time on response of the coated ion selective electrode were investigated. Finally the constructed electrode was used in complexometric and precipitation titrations of Tl{sup +} cation with EDTA and KBr, respectively. The response of the fabricated electrode at concentration range from 1.0 x 10{sup -8} to 1.0 x 10{sup -1}M is linear with a Nernstian slope of 57.27 mV.

  5. Miniaturizable Ion-Selective Arrays Based on Highly Stable Polymer Membranes for Biomedical Applications

    OpenAIRE

    Mònica Mir; Roberto Lugo; Islam Bogachan Tahirbegi; Josep Samitier

    2014-01-01

    Poly(vinylchloride) (PVC) is the most common polymer matrix used in the fabrication of ion-selective electrodes (ISEs). However, the surfaces of PVC-based sensors have been reported to show membrane instability. In an attempt to overcome this limitation, here we developed two alternative methods for the preparation of highly stable and robust ion-selective sensors. These platforms are based on the selective electropolymerization of poly(3,4-ethylenedioxythiophene) (PEDOT), where the sulfur at...

  6. Effect of fluoride-free and fluoridated carbamide peroxide gels on the hardness and surface roughness of aesthetic restorative materials

    Directory of Open Access Journals (Sweden)

    Homayoon Alaghehmand

    2013-01-01

    Full Text Available Background: Bleaching products may show some side effects on soft and hard tissues and restorative materials in the oral cavity. This study evaluated the effect of carbamide peroxide gel with and without fluoride ions on the microhardness and surface roughness of tooth-colored restorative materials. Materials and Methods: In this in-vitro study, 76 cubic specimens (4 mm 3 × 4 mm 3 × 3 mm 3 were fabricated from 4 aesthetic A3-shade restorative materials. These materials consisted of two composite resins and two glass ionomers. The specimens made from each material were treated with the following surface treatments: 1. Control group: The specimens were not bleached and were stored in normal saline. Group 2. Fluoridated 20% carbamide peroxide gel, treated 3 h a day for 4 weeks. Group 3. Treated 1 h a day with fluoride-less 22% carbamide peroxide for two weeks. From each group, three other specimens were selected to be evaluated in terms of changes in surface roughness, under scanning electron microscopy (SEM. Results: In this study, fluoridated 20% carbamide peroxide gel increased the microhardness of the four aesthetic restorative materials. The fluoride-free carbamide peroxide 22% reduced the microhardness of the four used materials, which this change was significant for Vitremer and Amelogen. SEM analyses showed changes in surface roughness of glass ionomer specimens. Conclusion: The effect of bleaching on the microhardness of restorative materials is material dependent. Before the application of bleaching systems on the glass ionomer materials, the application of a protective barrier should be considered.

  7. Private Well Water and Fluoride

    Science.gov (United States)

    ... well. What do I need to know about fluoride and groundwater from a well? Fluoride is present ... well has less than the recommended level of fluoride for preventing tooth decay? The recommended fluoride level ...

  8. Fluoride and Water (For Parents)

    Science.gov (United States)

    ... Teaching Kids to Be Smart About Social Media Fluoride and Water KidsHealth > For Parents > Fluoride and Water ... in healthy tooth development and cavity prevention. About Fluoride Fluoride, which exists naturally in water sources, is ...

  9. Infrared Spectroscopy of Ions in Selected Rotational and Spin-Orbit States

    Science.gov (United States)

    Jacovella, Ugo; Agner, Josef A.; Schmutz, Hansjürg; Merkt, Frederic

    2016-06-01

    First results are presented obtained using an experimental setup developed to record IR spectra of rotationally state-selected ions. The method we use is a state-selective version of a method developed by Schlemmer et al. to record IR spectra of ions. Ions are produced in specific rotational levels using mass-analysed threshold ionisation (MATI) spectroscopy combined with single-photon excitation of neutral molecules in supersonic expansions with a vacuum-ultraviolet laser. The ions generated by pulsed-field ionisation of Rydberg states of high principal quantum number (n ≈ 200) are extracted toward an octupole ion guide containing a neutral target gas. Prior to entering the octupole the ions are excited by an IR laser. The target gas is chosen so that only excited ions react to form product ions. These product ions are detected mass selectively as function of the IR laser wavenumber. To illustrate this method, we present IR spectra of C_2H_2^+ in selected rotational levels of the ^2Π3/2 and ^2Π1/2 spin-orbit components of the electronic ground state. Schlemmer et al., J. Chem. Phys. 117, 2068 (2002)

  10. Preparation of zirconium oxy ion-imprinted particle for the selective separation of trace zirconium ion from water.

    Science.gov (United States)

    Ren, Yueming; Liu, Pingxin; Liu, Xiaoli; Feng, Jing; Fan, Zhuangjun; Luan, Tianzhu

    2014-10-01

    Zr(IV) oxy ion-imprinted particle (Zr-IIP) was prepared using the metal ion imprinting technique in a sol-gel process on the surface of amino-silica. The dosages of zirconium ions as imprinted target, (3-aminopropyl) triethoxysilane (APTES) as a functional monomer and teraethyl orthosilicate (TEOS) as a cross-linker were optimized. The prepared Zr-IIP and Zr(IV) oxy ion non-imprinted particle (Zr-NIP) were characterized. pH effect, binding ability and the selectivity were investigated in detail. The results showed that the Zr-IIP had an excellent binding capacity and selectivity in the water. The equilibrium data fitted well to the pseudo-second-order kinetic and the Langmuir model for Zr(IV) binding onto Zr-IIP, respectively. The saturate binding capacity of Zr-IIP was found to be 196.08 μmol g(-1), which was 18 times higher than that of Zr-NIP. The sequence of binding efficiency of Zr-IIP for various ions was Zr(IV)>Cu(II)>Sb(III)>Eu(III). The coordination number has an important effect on the dimensional binding capacity. The equilibrium binding capacity of Zr-IIP for Zr(IV) decreased little under various concentrations of Pb(II) ions. The analysis of relative selectivity coefficient (Kr) indicated that the Zr-IIP had an appreciable binding specificity towards Zr(IV) although the competitive ions coexisted in the water. The Zr-IIP could serve as an efficient selective material for recovering or removing zirconium from the water environment.

  11. Mobility-Selected Ion Trapping and Enrichment Using Structures for Lossless Ion Manipulations.

    Science.gov (United States)

    Chen, Tsung-Chi; Ibrahim, Yehia M; Webb, Ian K; Garimella, Sandilya V B; Zhang, Xing; Hamid, Ahmed M; Deng, Liulin; Karnesky, William E; Prost, Spencer A; Sandoval, Jeremy A; Norheim, Randolph V; Anderson, Gordon A; Tolmachev, Aleksey V; Baker, Erin S; Smith, Richard D

    2016-02-02

    The integration of ion mobility spectrometry (IMS) with mass spectrometry (MS) and the ability to trap ions in IMS-MS measurements is of great importance for performing reactions, accumulating ions, and increasing analytical measurement sensitivity. The development of Structures for Lossless Ion Manipulations (SLIM) offers the potential for ion manipulations in an extended and more effective manner, while opening opportunities for many more complex sequences of manipulations. Here, we demonstrate an ion separation and trapping module and a method based upon SLIM that consists of a linear mobility ion drift region, a switch/tee and a trapping region that allows the isolation and accumulation of mobility-separated species. The operation and optimization of the SLIM switch/tee and trap are described and demonstrated for the enrichment of the low abundance ions. A linear improvement in ion intensity was observed with the number of trapping/accumulation events using the SLIM trap, illustrating its potential for enhancing the sensitivity of low abundance or targeted species.

  12. Molten fluorides for nuclear applications

    Directory of Open Access Journals (Sweden)

    Sylvie. Delpech

    2010-12-01

    Full Text Available The importance of pyrochemistry is being increasingly acknowledged and becomes unavoidable in the nuclear field. Molten salts may be used for fuel processing and spent fuel recycling, for heat transfer, as a homogeneous fuel and as a breeder material in fusion systems. Fluorides that are stable at high temperature and under high neutron flux are especially promising. Analysis of several field cases reveals that corrosion in molten fluorides is essentially due to the oxidation of metals by uranium fluoride and/or oxidizing impurities. The thermodynamics of this process are discussed with an emphasis on understanding the mass transfer in the systems, selecting appropriate metallic materials and designing effective purification methods.

  13. Fluoride varnish or fluoride mouth rinse?

    DEFF Research Database (Denmark)

    Keller, M K; Klausen, B J; Twetman, S

    2016-01-01

    OBJECTIVE: In many Danish communities, school-based fluoride programs are offered to children with high caries risk in adjunct to tooth brushing. The purpose of this field trial was to compare the caries-preventive effectiveness of two different fluoride programs in 6-12 year olds. BASIC RESEARCH...... different schools were enrolled after informed consent and their class unit was randomly allocated to one of two fluoride programs. INTERVENTIONS: One group received a semi-annual fluoride varnish applications (FV) and the other group continued with an existing program with fluoride mouth rinses once per...... in caries development over two years among children participating in a school-based fluoride varnish or mouth rinse program....

  14. Decontamination of soils and materials containing medium-fired PuO{sub 2} using inhibited fluorides with polymer filtration technology

    Energy Technology Data Exchange (ETDEWEB)

    Temer, D.J.; Villarreal, R.; Smith, B.F. [Los Alamos National Lab., NM (United States)

    1997-10-01

    The decontamination of soils and/or materials from medium-fired plutonium oxide (PuO{sub 2}) with an effective and efficient decontamination agent that will not significantly dissolve the matrix requires a new and innovative technology. After testing several decontamination agents and solutions for dissolution of medium-fired PuO{sub 2}, the most successful decontamination solutions were fluoride compounds, which were effective in breaking the Pu-oxide bond but would not extensively dissolve soil constituents and other materials. The fluoride compounds, tetra fluoboric acid (HBF{sub 4}) and hydrofluorosilicic acid (H{sub 2}F{sub 6}Si), were effective in dissolving medium-fired PuO{sub 2}, and did not seem to have the potential to dissolve the matrix. In both compounds, the fluoride atom is attached to a boron or silicon atom that inhibits the reactivity of the fluoride towards other compounds or materials containing atoms less attracted to the fluoride atom in an acid solution. Because of this inhibition of the reactivity of the fluoride ion, these compounds are termed inhibited fluoride compounds or agents. Both inhibited fluorides studied effectively dissolved medium-fired PuO{sub 2} but exhibited a tendency to not attack stainless steel or soil. The basis for selecting inhibited fluorides was confirmed during leaching tests of medium-fired PuO{sub 2} spiked into soil taken from the Idaho National Engineering Laboratory (INEL). When dissolved in dilute HNO{sub 3}, HCl, or HBr, both inhibited fluoride compounds were effective at solubilizing the medium-fired PuO{sub 2} from spiked INEL soil.

  15. Circumventing Traditional Conditioning Protocols in Polymer Membrane-Based Ion-Selective Electrodes.

    Science.gov (United States)

    Rich, Michelle; Mendecki, Lukasz; Mensah, Samantha T; Blanco-Martinez, Enrique; Armas, Stephanie; Calvo-Marzal, Percy; Radu, Aleksandar; Chumbimuni-Torres, Karin Y

    2016-09-06

    Preparation of ion-selective electrodes (ISEs) often requires long and complicated conditioning protocols limiting their application as tools for in-field measurements. Herein, we eliminated the need for electrode conditioning by loading the membrane cocktail directly with primary ion solution. This proof of concept experiment was performed with iodide, silver, and sodium selective electrodes. The proposed methodology significantly shortened the preparation time of ISEs, yielding functional electrodes with submicromolar detection limits. Moreover, it is anticipated that this approach may form the basis for the development of miniaturized all-solid-state ion-selective electrodes for in situ measurements.

  16. Influence of the method of fluoride administration on toxicity and fluoride concentrations in Japanese quail

    Science.gov (United States)

    Fleming, W.J.; Schuler, C.A.

    1988-01-01

    Young Japanese quail (Coturnix japonica) were administered NaF for 16 d either in their diet or by esophageal intubation. Based on the total fluoride ion (Emg F-) intake over the l6-d experimental period, fluoride administered by intubation was at least six times more toxic than that fed in the diet. Dietary concentrations of 1,000 ppm F- (Emg F- for 16 d = approx. 144) produced no mortality, whereas intubated doses produced 73% or greater mortality in all groups administered 54 mg F- /kg/d or more (Emg F- for 16 d _ approx. 23 mg). GraphIc companson of the regression of log F- ppm in femurs/mg F- intake showed that fluoride levels in the femurs of quail administered fluoride by intubation were higher than in those administered fluoride in the diet.

  17. Comparison of effects of diode laser and CO2 laser on human teeth and their usefulness in topical fluoridation.

    Science.gov (United States)

    González-Rodríguez, Alberto; de Dios López-González, Juan; del Castillo, Juan de Dios Luna; Villalba-Moreno, Juan

    2011-05-01

    Various authors have reported more effective fluoridation from the use of lasers combined with topical fluoride than from conventional topical fluoridation. Besides the beneficial effect of lasers in reducing the acid solubility of an enamel surface, they can also increase the uptake of fluoride. The study objectives were to compare the action of CO(2) and GaAlAs diode lasers on dental enamel and their effects on pulp temperature and enamel fluoride uptake. Different groups of selected enamel surfaces were treated with amine fluoride and irradiated with CO(2) laser at an energy power of 1 or 2 W or with diode laser at 5 or 7 W for 15 s each and compared to enamel surfaces without treatment or topical fluoridated. Samples were examined by means of environmental scanning electron microscopy (ESEM). Surfaces of all enamel samples were then acid-etched, measuring the amount of fluoride deposited on the enamel by using a selective ion electrode. Other enamel surfaces selected under the same conditions were irradiated as described above, measuring the increase in pulp temperature with a thermocouple wire. Fluorination with CO(2) laser at 1 W and diode laser at 7 W produced a significantly greater fluoride uptake on enamel (89 ± 18 mg/l) and (77 ± 17 mg/l) versus topical fluoridation alone (58 ± 7 mg/l) and no treatment (20 ± 1 mg/l). Diode laser at 5 W produced a lesser alteration of the enamel surface compared to CO(2) laser at 1 W, but greater pulp safety was provided by CO(2) laser (ΔT° 1.60° ± 0.5) than by diode laser (ΔT° 3.16° ± 0.6). Diode laser at 7 W and CO(2) laser at 2 W both caused alterations on enamel surfaces, but great pulp safety was again obtained with CO(2) (ΔT° 4.44° ± 0.60) than with diode (ΔT° 5.25° ± 0.55). Our study demonstrates that CO(2) and diode laser irradiation of the enamel surface can both increase fluoride uptake; however, laser energy parameters must be carefully

  18. Thermal responsive ion selectivity of uranyl peroxide nanocages: an inorganic mimic of K{sup +} ion channels

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yunyi; Sun, Xinyu; Liu, Tianbo [Department of Polymer Science, University of Akron, Akron, OH (United States); Szymanowski, Jennifer E.S.; Burns, Peter C. [Department of Civil Engineering and Geological Sciences, University of Notre Dame, Notre Dame, IN (United States)

    2016-06-06

    An actinyl peroxide cage cluster, Li{sub 48+m}K{sub 12}(OH){sub m}[UO{sub 2}(O{sub 2})(OH)]{sub 60} (H{sub 2}O){sub n} (m∼20 and n∼310; U{sub 60}), discriminates precisely between Na{sup +} and K{sup +} ions when heated to certain temperatures, a most essential feature for K{sup +} selective filters. The U{sub 60} clusters demonstrate several other features in common with K{sup +} ion channels, including passive transport of K{sup +} ions, a high flux rate, and the dehydration of U{sub 60} and K{sup +} ions. These qualities make U{sub 60} (a pure inorganic cluster) a promising ion channel mimic in an aqueous environment. Laser light scattering (LLS) and isothermal titration calorimetry (ITC) studies revealed that the tailorable ion selectivity of U{sub 60} clusters is a result of the thermal responsiveness of the U{sub 60} hydration shells. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Thermal responsive ion selectivity of uranyl peroxide nanocages. An inorganic mimic of K{sup +} ion channels

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yunyi; Sun, Xinyu; Liu, Tianbo [Akron Univ., OH (United States). Dept. of Polymer Science; Szymanowski, Jennifer E.S.; Burns, Peter C. [Notre Dame Univ., IN (United States). Dept. of Civil Engineering and Geological Sciences

    2016-06-06

    An actinyl peroxide cage cluster, Li{sub 48+m}K{sub 12}(OH){sub m}[UO{sub 2}(O{sub 2})(OH)]{sub 60} (H{sub 2}O){sub n} (m∼20 and n∼310; U{sub 60}), discriminates precisely between Na{sup +} and K{sup +} ions when heated to certain temperatures, a most essential feature for K{sup +} selective filters. The U{sub 60} clusters demonstrate several other features in common with K{sup +} ion channels, including passive transport of K{sup +} ions, a high flux rate, and the dehydration of U{sub 60} and K{sup +} ions. These qualities make U{sub 60} (a pure inorganic cluster) a promising ion channel mimic in an aqueous environment. Laser light scattering (LLS) and isothermal titration calorimetry (ITC) studies revealed that the tailorable ion selectivity of U{sub 60} clusters is a result of the thermal responsiveness of the U{sub 60} hydration shells.

  20. Ion selective electrode for determination of chloride ion in biological materials, food products, soils and waste water.

    Science.gov (United States)

    Sekerka, I; Lechner, J F

    1978-11-01

    The chloride ion selective electrode is used for a rapid, simple, and reliable determination of chloride ion in biological materials (blood serum, urine, fish, and plant tissues), food products (milk, beef extract, nutrient broth and orange, tomato, and grapefruit juices), soils, and waste water (industrial and municipal). The method consists of treating the samples with perchloric acid (pH 1) and potassium peroxydisulfate and determining the chloride content either by a calibration curve or by known addition or analyte addition, using the chloride ion selective electrode. Such sample treatment eliminates most of the interferences occurring in the samples, including iodide, complexing and reducing compounds, and macromolecular and surface-active species. The method is suitable for a wide range of chloride concentration, e.g., 5010 ppm Cl- in nutrient broth and 4890 ppm in beef extract and as low as 12 and 80 ppm in soil extracts.

  1. Effect of Background Ions on the Selection of the Discharge Path

    Institute of Scientific and Technical Information of China (English)

    HE Zheng-Hao; LI Jin

    2001-01-01

    The effects of the background ions on the selection of the discharge path in an air gap have been studied with two different methods. The lightning impulse air discharge experiment is conducted using an independent ion generator, while the air discharge experiment uses a lightning impulse superimposed on a dc high voltage used to produce background ions. The influence of different background ions on the leader development, and thus on the discharge path, is observed. Consistent results have been obtained with the two methods. The probability for the discharge path passing through the negative ion space is much higher than that for the passing through the positive ion space. The mechanism of the effects of background ions is analysed based on the eleetron avalanche and the electric field.

  2. Control of ion selectivity in LeuT: two Na+ binding sites with two different mechanisms.

    Science.gov (United States)

    Noskov, Sergei Y; Roux, Benoît

    2008-03-28

    The x-ray structure of LeuT, a bacterial homologue of Na(+)/Cl(-)-dependent neurotransmitter transporters, provides a great opportunity to better understand the molecular basis of monovalent cation selectivity in ion-coupled transporters. LeuT possesses two ion binding sites, NA1 and NA2, which are highly selective for Na(+). Extensive all-atom free-energy molecular dynamics simulations of LeuT embedded in an explicit membrane are performed at different temperatures and various occupancy states of the binding sites to dissect the molecular mechanism of ion selectivity. The results show that the two binding sites display robust selectivity for Na(+) over K(+) or Li(+), the competing ions of most similar radii. Of particular interest, the mechanism primarily responsible for selectivity for each of the two binding sites appears to be different. In NA1, selectivity for Na(+) over K(+) arises predominantly from the strong electrostatic field arising from the negatively charged carboxylate group of the leucine substrate coordinating the ion directly. In NA2, which comprises only neutral ligands, selectivity for Na(+) is enforced by the local structural restraints arising from the hydrogen-bonding network and the covalent connectivity of the polypeptide chain surrounding the ion according to a "snug-fit" mechanism.

  3. Low-energy state-selective charge transfer by multiply charged ions

    NARCIS (Netherlands)

    Lubinski, G; Juhasz, Z; Morgenstern, R; Hoekstra, R

    2001-01-01

    We present a combined rf-guided ion beam and photon emission spectroscopy method, which facilitates state-selective charge-transfer measurements at energies of direct relevance for astrophysics and fusion-plasma diagnostics and modeling. Ion energies have been varied from 1000 eV/amu down to energie

  4. Fluoride release and uptake capacities of fluoride-releasing restorative materials.

    Science.gov (United States)

    Attar, Nuray; Turgut, Melek D

    2003-01-01

    Many fluoride-releasing dental materials are being sold on the basis of their cariostatic properties. However, the amount fluoride release of these materials is still uncertain. This study investigated the fluoride release and uptake characteristics of four flowable resin composites (Heliomolar Flow, Tetric Flow, Wave, Perma Flo), one flowable compomer (Dyract flow), one conventional glass ionomer cement mixed with two different powder/liquid ratios (ChemFlex Syringeable and ChemFlex Condensable), one packable resin composite (SureFil), one ion-releasing composite (Ariston pHc) and one resin-modified glass ionomer cement (Vitremer). Seven discs (6-mm diameter and 1.5-mm height) were prepared for each material. Each disc was immersed in 3.5 ml of deionized water within a plastic vial and stored at 37 degrees C. The deionized water was changed every 24 hours and the release of fluoride was measured for 30 days. At the end of this period, the samples were recharged with 2 ml of 1.23% acidulated phosphate fluoride (APF) gel for four minutes. Then, all samples were reassessed for an additional 10 days. The fluoride release of all samples was measured with a specific fluoride electrode and an ionanalyzer. Statistical analyses were conducted using two-way repeated measure ANOVA and Duncan's multiple range tests. For all tested materials, the greatest fluoride release was observed after the first day of the study (p0.05). Ariston pHc released the highest amount of fluoride, followed by ChemFlex Syringeable, Vitremer and ChemFlex Condensable. There were statistically significant differences among these materials (p<0.05). Fluoride release of all materials were significantly increased after the first day following refluoridation and Ariston pHc released the greatest among all materials (p<0.01). At the end of two days of refluoridation, the fluoride release rate for each material dropped quickly and stabilized within three days.

  5. Fluoride in diet

    Science.gov (United States)

    Diet - fluoride ... bones and teeth. Too much fluoride in the diet is very rare. Rarely, infants who get too ... of essential vitamins is to eat a balanced diet that contains a variety of foods from the ...

  6. Controlled Synthesis of a Novel Heteropolymetallic Complex with Selectively Incorporated Lanthanide(III) Ions

    OpenAIRE

    Debroye, Elke; Ceulemans, Matthias; Vander Elst, Luce; Laurent, Sophie; Muller, Robert N.; Parac-Vogt, Tatjana

    2014-01-01

    A novel synthetic strategy toward a heteropolymetallic lanthanide complex with selectively incorporated gadolinium and europium ions is outlined. Luminescence and relaxometric measurements suggest possible applications in bimodal (magnetic resonance/optical) imaging.

  7. Media selection in ion-exchange chromatography in a single microplate.

    Science.gov (United States)

    Cabanne, Charlotte; Santarelli, Xavier

    2014-01-01

    High-throughput process development is more and more used in chromatography. Limitations are the tools provided by the manufacturers. Here, we describe a method to select chromatographic media for ion-exchange chromatography using a 96-well filter microplate.

  8. Ion-selective electrodes in organic elemental and functional group analysis: a review

    Energy Technology Data Exchange (ETDEWEB)

    Selig, W.

    1977-11-08

    The literature on the use of ion-selective electrodes in organic elemental and functional group analysis is surveyed in some detail. The survey is complete through Chemical Abstracts, Vol. 83 (1975). 40 figures, 52 tables, 236 references.

  9. Fluoride release, recharge and flexural properties of polymethylmethacrylate containing fluoridated glass fillers.

    Science.gov (United States)

    Al-Bakri, I A; Swain, M V; Naoum, S J; Al-Omari, W M; Martin, E; Ellakwa, A

    2014-06-01

    The purpose of this study was to investigate the effect of fluoridated glass fillers on fluoride release, recharge and the flexural properties of modified polymethylmethacrylate (PMMA). Specimens of PMMA denture base material with various loading of fluoridated glass fillers (0%, 1%, 2.5%, 5% and 10% by weight) were prepared. Flexural properties were evaluated on rectangular specimens (n = 10) aged in deionized water after 24 hours, 1 and 3 months. Disc specimens (n = 10) were aged for 43 days in deionized water and lactic acid (pH 4.0) and fluoride release was measured at numerous intervals. After ageing, specimens were recharged and fluoride re-release was recorded at 1, 3 and 7 days after recharge. Samples containing 2.5%, 5% and 10% glass fillers showed significantly (p glass fillers specimens. All experimental specimens exhibited fluoride release in both media. The flexural strength of specimens decreased in proportion to the percentage filler inclusion with the modulus of elasticity values remaining within ISO Standard 1567. The modified PMMA with fluoridated glass fillers has the ability to release and re-release fluoride ion. Flexural strength decreased as glass filler uploading increased. © 2014 Australian Dental Association.

  10. Tuning the chemical selectivity of SWNT-FETs for detection of heavy-metal ions.

    Science.gov (United States)

    Forzani, Erica S; Li, Xiulan; Zhang, Peiming; Tao, Nongjian; Zhang, Ruth; Amlani, Islamshah; Tsui, Raymond; Nagahara, Larry A

    2006-11-01

    A method to functionalize single-walled carbon nanotubes (SWNTs) in a field-effect transistor (FET) device for the selective detection of heavy-metal ions is presented. In this method, peptide-modified polymers were electrochemically deposited onto SWNTs and the selective detection of metal ions was demonstrated by choosing appropriate peptide sequences. The signal transduction mechanism of the peptide-modified SWNT-FETs has also been studied.

  11. Electrochemical selective ion separation in capacitive deionization with sodium manganese oxide.

    Science.gov (United States)

    Kim, Seonghwan; Yoon, Hansun; Shin, Dongyoon; Lee, Jaehan; Yoon, Jeyong

    2017-11-15

    Electrochemical selective ion separation via capacitive deionization, for example, separation of lithium resource from brine, using lithium ion batteries is proposed and demonstrated to have the potential for separating specific ions selectively from a solution containing diverse ions. This separation method is of great industrial concern because of applicability in various fields such as deionization, water softening, purification, heavy metal removal, and resource recovery. Nevertheless, besides the selectivity of materials for lithium ion batteries toward Li(+), there is very little investigation on the selectivity of the materials for sodium ion batteries toward Na(+). Here, the electrochemical selectivity of sodium manganese oxide (Na0.44MnO2), one of the most widely used material in sodium ion batteries, for Na(+) and other cations (K(+), Mg(2+), and Ca(2+)) is investigated. Selective Na(+) separation using the system consisting of Na0.44MnO2 and a Ag/AgCl electrode is successfully demonstrated from a solution containing diverse cations (Na(+), K(+), Mg(2+), and Ca(2+)) via a two-step process that involves a capturing step (charging process) and a releasing step (discharging process). The results showed that Na0.44-xMnO2 has over 13 times higher selectivity for Na(+) than for K(+) and 6-8times higher selectivity for Na(+) than for Mg(2+) and Ca(2+) in the electrolyte containing equal concentrations of the respective ions. Additionally, as a practical demonstration, Na(+) was successfully separated from an industrial raw material used for pure KOH production (estimated ratio of Na(+):K(+)=1:200). Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Review of progresses on clinical applications of ion selective electrodes for electrolytic ion tests: from conventional ISEs to graphene-based ISEs

    OpenAIRE

    Rongguo Yan; Shuai Qiu; Lei Tong; Yin Qian

    2016-01-01

    There exist several positively and negatively charged electrolytes or ions in human blood, urine, and other body fluids. Tests that measure the concentration of these ions in clinics are performed using a more affordable, portable, and disposable potentiometric sensing method with few sample volumes, which requires the use of ion-selective electrodes (ISEs) and reference electrodes. This review summarily descriptively presents progressive developments and applications of ion selective electro...

  13. Fluoride release of two fluoride-containing flowable resins in vitro%两种含氟流动树脂释氟能力的体外研究

    Institute of Scientific and Technical Information of China (English)

    马京秀; 李涢

    2014-01-01

    目的:体外比较2种含氟流动树脂Beautifil Flow Plus F00和Dyad Flow的短期释氟量,以探讨2种材料释氟能力的差异。方法选取含氟流动树脂F00、DF和不含氟树脂Valux,制备直径10mm,厚1mm的样本,每组10个。将样本分别浸泡于5ml去离子水,第1、2、3、7、14、21、28d使用氟离子选择电极测量去离子水中的氟离子浓度,Va组为对照,比较F00和DF组前3d的单日氟释放及28d内各时间点的累积氟释放情况。结果 F00和Dyad Flow的释氟浓度均第1d最高;前3d单日释氟浓度呈下降趋势,差异有统计学意义(P<0.01);28d内2实验组均有缓慢持续的氟释放,随着时间延长累积释氟量增加;各个时间点,Dyad Flow组累积释氟量高于F00组,差异有统计学意义(P<0.01)。结论2种含氟流动树脂F00和Dyad Flow第1d氟释放最多,在测试时间内均有低量但持续的释氟能力,Dyad Flow释氟量略高于F00。%Objective To compare the amount of fluoride release of two fluoride-containing flowable resins Beautifil Flow Plus F00 (F00) and Dyad Flow (DF). Methods Two fluoride-containing flowable resins F00 and DF and one fluoride-free resin Valux ( Va ) were selected. Ten samples ( 10mm × 1mm ) of each material were prepared respectively. Each sample was placed into 5 ml de-ionized water and the amount of fluoride released into the de-ionized water was measured by fluoride ion selective electrode at 1, 2, 3, 7, 14, 21 and 28d, respectively. The amount of fluoride release in the first three days and cumulative amount of fluoride release at each time point were calculated for the three materials, with F00 and DF being the test groups and Va being the control group. Results The concentration of fluoride release was the highest in F00 and DF in the first day(0. 0952 ± 0. 0200ug/ml and 0. 1362 ± 0. 0179ug/ml)and decreased significantly during the first three days ( P <0. 01 ) . Both of the fluoride-containing resins exhibited sustained

  14. Selected Experimental Results from Heavy-Ion Collisions at LHC

    Directory of Open Access Journals (Sweden)

    Ranbir Singh

    2013-01-01

    Full Text Available We review a subset of experimental results from the heavy-ion collisions at the Large Hadron Collider (LHC facility at CERN. Excellent consistency is observed across all the experiments at the LHC (at center of mass energy sNN=2.76 TeV for the measurements such as charged particle multiplicity density, azimuthal anisotropy coefficients, and nuclear modification factor of charged hadrons. Comparison to similar measurements from the Relativistic Heavy Ion Collider (RHIC at lower energy (sNN=200 GeV suggests that the system formed at LHC has a higher energy density and larger system size and lives for a longer time. These measurements are compared to model calculations to obtain physical insights on the properties of matter created at the RHIC and LHC.

  15. Seasonal Variation in Fluoride Content in Groundwaters of Langtang Area, Northcentral Nigeria

    Science.gov (United States)

    Dibal, H. U.; Dajilak, W. N.; Lekmang, I. C.; Nimze, L. W.; Yenne, E. Y.

    2017-06-01

    Thirty groundwater samples were collected at the peak of the rainy season and analysed for fluoride and other cations and anions in drinking water sources of Langtang area. For comparative purposes, thirty seven groundwater samples were collected in the dry season. The aim of the study was to determine variation in fluoride content with respect to the seasons. Fluoride in water was determined by the Ion Selective Electrode (ISE) and the cations by the Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The anion (sulphate) was determined by Multi - Ion Colorimeter, bicarbonate and chloride by titration method. In addition fluorine content in aquifer materials from a borehole section were determined by Fusion method. The two seasons show variation in content of fluoride in groundwater. Fluoride content in groundwater is higher in the dry season ranging from 0.13 - 10.3 mg/l compared to the 0.06 - 4.60 mg/l values in the rainy season. Content of fluorine (0.01 wt %) in the aquifer materials (sands) is low from depth of 0 to 7.95 m. However, fluorine content increases with depth, from 7.95 to 10.60 m with concentration of 0.04 wt %, 0.05 wt % from 10.60 to 13.25m, and 0.07 wt % from 13.25 to 15.70 m, the content of fluorine however, decreased at depth 15.70 to18.55m with concentration of 0.02 wt % even with fluorite mineral in the aquifer material at this depth. Dilution of fluoride ion as a result of rain input which recharges the aquifer may be the main reason for lower values recorded in the rainy season. Over fifty and sixty percent of waters in both dry and rainy season have fluoride concentration above the WHO upper limit of 1.5 mg/l. Consumption of these elevated values of fluoride in groundwater of the study area, clearly manifests as symptoms of dental fluorosis.

  16. Direct ion speciation analysis with ion-selective membranes operated in a sequential potentiometric/time resolved chronopotentiometric sensing mode.

    Science.gov (United States)

    Ghahraman Afshar, Majid; Crespo, Gastón A; Bakker, Eric

    2012-10-16

    Ion-selective membranes based on porous polypropylene membranes doped with an ionophore and a lipophilic cation-exchanger are used here in a new tandem measurement mode that combines dynamic electrochemistry and zero current potentiometry into a single protocol. Open circuit potential measurements yield near-nernstian response slopes in complete analogy to established ion-selective electrode methodology. Such measurements are well established to give direct information on the so-called free ion concentration (strictly, activity) in the sample. The same membrane is here also operated in a constant current mode, in which the localized ion depletion at a transition time is visualized by chronopotentiometry. This dynamic electrochemistry methodology gives information on the labile ion concentration in the sample. The sequential protocol is established on potassium and calcium ion-selective membranes. An increase of the ionophore concentration in the membrane to 180 mM makes it possible to determine calcium concentrations as high as 3 mM by chronopotentiometry, thereby making it possible to directly detect total calcium in undiluted blood samples. Recovery times after current perturbation depend on the current amplitude but can be kept to below 1 min for the polypropylene based ion-selective membranes studied here. Plasticized PVC as membrane material is less suited for this protocol, especially when the measurement at elevated concentrations is desired. An analysis of current amplitudes, transition times, and concentrations shows that the data are described by the Sand equation and that migration effects are insignificant. A numerical model describes the experimental findings with good agreement and gives guidance on the required selectivity in order to observe a well-resolved transition time and on the expected errors due to insufficient selectivity. The simulations suggest that the methodology compares well to that of open circuit potentiometry, despite giving

  17. ADSORPTION SELECTIVITY FOR Cu2+,Ni2+,Co2+IONS USING CROSSLINKING CHITOSAN RESINS IMPRINTED BY METAL IONS

    Institute of Scientific and Technical Information of China (English)

    HUANGWenqiang; HANLijun; 等

    1999-01-01

    Metal ion-imprintedly crosslinked chitosan resin 1 and resin 2 were prepared by the use of Cu2+ and Ni2+ as template ions and glutaraldehyde as crosslinking agent,respectively,Through investigation on the adsorption capacties and binding constants for Cu2+,Ni2+ and Co2+ ions on chitosan resins,resin 1 and resin 2 exhibit the adsorption selectivity for the mixture solution of 1L1 Cu2+ and Ni2+ ions.The adsorption selectivity of metal ion-imprinted resins for their template ions in much higher than that of uncrosslinked chitosan resin.

  18. Dopant Selective Reactive Ion Etching of Silicon Carbide

    Science.gov (United States)

    Okojie, Robert (Inventor)

    2016-01-01

    A method for selectively etching a substrate is provided. In one embodiment, an epilayer is grown on top of the substrate. A resistive element may be defined and etched into the epilayer. On the other side of the substrate, the substrate is selectively etched up to the resistive element, leaving a suspended resistive element.

  19. Water fluoridation in 40 Brazilian cities: 7 year analysis

    Directory of Open Access Journals (Sweden)

    Suzely Adas Saliba MOIMAZ

    2013-01-01

    Full Text Available Objectives Fluoride levels in the public water supplies of 40 Brazilian cities were analyzed and classified on the basis of risk/benefit balance. Material and Methods Samples were collected monthly over a seven-year period from three sites for each water supply source. The samples were analyzed in duplicate in the laboratory of the Center for Research in Public Health - UNESP using an ion analyzer coupled to a fluoride-specific electrode. Results A total of 19,533 samples were analyzed, of which 18,847 were artificially fluoridated and 686 were not artificially fluoridated. In samples from cities performing water fluoridation, 51.57% (n=9,720 had fluoride levels in the range of 0.55 to 0.84 mg F/L; 30.53% (n=5,754 were below 0.55 mg F/L and 17.90% (n=3,373 were above 0.84 mg F/L (maximum concentration=6.96 mg F/L. Most of the cities performing fluoridation that had a majority of samples with fluoride levels above the recommended parameter had deep wells and more than one source of water supply. There was some variability in the fluoride levels of samples from the same site and between collection sites in the same city. Conclusions The majority of samples from cities performing fluoridation had fluoride levels within the range that provides the best combination of risks and benefits, minimizing the risk of dental fluorosis while preventing dental caries. The conduction of studies about water distribution systems is suggested in cities with high natural fluoride concentrations in order to optimize the use of natural fluoride for fluoridation costs and avoid the risk of dental fluorosis.

  20. Dental fluorosis, fluoride in urine, and nutritional status in adolescent students living in the rural areas of Guanajuato, Mexico.

    Science.gov (United States)

    Del Carmen, Aguilar-Díaz Fatima; Javier, de la Fuente-Hernández; Aline, Cintra-Viveiro Cristina

    2016-01-01

    The aim of this study was to assess urine fluoride concentration, nutritional status, and dental fluorosis in adolescent students living in the rural areas of Guanajuato, Mexico. A cross-sectional study was conducted including participants aged 11-20 years. The presence and severity of dental fluorosis was registered according to the Thylstrup and Fejerskov index (TFI) criteria. Anthropometric measures were also recorded. Urine sample of the first morning spot was recollected to assess urine fluoride concentration by using the potentiometric method with an ion-selective electrode. Water samples were also recollected and analyzed. Bivariate tests were performed to compare urine fluoride concentration according to different variables such as sex, body mass index, and TFI. Nonparametric tests were used. A logistic regression model was performed (SPSS® 21.0). This study included 307 participants with a mean age of 15.6 ± 1.6; 62.5% of the participants showed normal weight. A total of 91.9% of the participants had dental fluorosis, and 61.6% had TFI > 4. Mean fluoride content in urine ranged between 0.5 and 6.65 mg/L, with a mean of 1.27 ± 1.2 mg/L. Underweight children showed greater urine fluoride concentration. The increment of urine fluoride was a related (OR = 1.40) to having severe dental fluorosis. Most of the studied population had moderate or severe dental fluorosis. Urine fluoride concentration was related to fluorosis severity and nutritional status. Underweight children showed greater urine fluoride concentration as well as severe dental fluorosis.

  1. Transport-limited water splitting at ion-selective interfaces during concentration polarization

    CERN Document Server

    Nielsen, Christoffer P

    2013-01-01

    We present an analytical model of salt- and water-ion transport across an ion-selective interface based on an assumption of local equilibrium of the water-dissociation reaction. The model yields current-voltage characteristics and curves of water-ion current versus salt-ion current, which are in qualitative agreement with experimental results published in the literature. The analytical results are furthermore in agreement with direct numerical simulations. As part of the analysis, we find approximate solutions to the classical problem of pure salt transport across an ion-selective interface. These solutions provide closed-form expressions for the current-voltage characteristics, which include the overlimiting current due to the development of an extended space charge region. Finally, we discuss how the addition of an acid or a base affects the transport properties of the system and thus provide predictions accessible to further experimental tests of the model.

  2. Ion-selective supported liquid membranes placed under steady-state diffusion control.

    Science.gov (United States)

    Tompa, Károly; Birbaum, Karin; Malon, Adam; Vigassy, Tamás; Bakker, Eric; Pretsch, Ernö

    2005-12-01

    Supported liquid membranes are used here to establish steady-state concentration profiles across ion-selective membranes rapidly and reproducibly. This opens up new avenues in the area of nonequilibrium potentiometry, where reproducible accumulation and depletion processes at ion-selective membranes may be used to gain valuable analytical information about the sample. Until today, drifting signals originating from a slowly developing concentration profile across the ion-selective membrane made such approaches impractical in zero current potentiometry. Here, calcium- and silver-selective membranes were placed between two identical aqueous electrolyte solutions, and the open circuit potential was monitored upon changing the composition of one solution. Steady state was reached in approximately 1 min with 25-microm porous polypropylene membranes filled with bis(2-ethylhexyl) sebacate doped with ionophore and lipophilic ion exchanger. Ion transport across the membrane resulted on the basis of nonsymmetric ion-exchange processes at both membrane sides. The steady-state potential was calculated as the sum of the two membrane phase boundary potentials, and good correspondence to experiment was observed. Concentration polarizations in the contacting aqueous phases were confirmed with stirring experiments. It was found that interferences (barium in the case of calcium electrodes and potassium with silver electrodes) induce a larger potential change than expected with the Nicolsky equation because they influence the level of polarization of the primary ion (calcium or silver) that remains potential determining.

  3. Calix[4]arene-Based New Neutral Sensors for Fluoride

    Institute of Scientific and Technical Information of China (English)

    LIU,Shun-Ying; MENG,Ling-Zhi; LIU,Xin; HE,Yong-Bing

    2004-01-01

    @@ The development of new receptors which can recognize neutral and charged species has attracted considerable interest in the recent past.[1] Anions such as fluoride, chloride, phosphate and carboxylate play crucial roles in a range of biological phenomena and are implicated in many disease states.[2] Investigations on molecular and/or ionic recognition by calixarenes and their derivatives as synthetic receptors have attracted increasing attention in supramolecular chemistry because of their modifiable structure.[3] However, calix[4]arenes-based neutral receptors containing thiourea and amide groups are still rare. In this paper, we report fluoride selective optical chemosensors 4 and 5, based on calix[4]arene thiourea and amide derivatives, which only show a remarkable absorption change in the presence of fluoride ions, while have no any change upon addition of other anions (Cl- Br-, I-, AcO- and H2PO4-). The association constants are 947 and 2883 mol·L-1, respectively. The synthesis of calix[4]arene derivatives 4 and 5 is outlined in the following Scheme 1.

  4. A cathode material based on the iron fluoride with an ultra-thin Li3FeF6 protective layer for high-capacity Li-ion batteries

    Science.gov (United States)

    Yang, Juan; Xu, Zhanglin; Zhou, Haochen; Tang, Jingjing; Sun, Hongxu; Ding, Jing; Zhou, Xiangyang

    2017-09-01

    Iron fluoride based on the multi-electron reaction is a typical representative among the new-style cathode materials for Lithium-ion batteries, which is attracting extensive attentions. To relieve the cathode dissolution and interfacial side reactions and improve the electrochemical performance of FeF3·0.33H2O, we design an ultra-thin Li3FeF6 protective layer, which is in-situ formed on the surface of FeF3·3H2O particles by a facile process. The prepared Li3FeF6/FeF3·0.33H2O (LF50) composite displays a superior rate performance (152 mAh g-1 at 1000 mA g-1), which is remarkable to many other carbon-free iron fluorides. And it is noticeable that a reversible capacity of 174 mAh g-1 can be retained after 100 cycles, indicating an outstanding cycling stability contrast to the bare FeF3·0.33H2O. The enhanced electrochemical performance is attributed to the protection of Li3FeF6 layer which reduces the cathode dissolution and interfacial side reactions. Moreover, the agglomeration of first particles in the calcination process is effectively suppressed resulting from the introduction of the Li3FeF6 protective layer, which promotes electrolyte penetration and charge transfer in the composites. It is expected that the strategy can provide a new approach for the modification of other metal fluoride.

  5. Corrosion resistance of stainless steel, nickel-titanium, titanium molybdenum alloy, and ion-implanted titanium molybdenum alloy archwires in acidic fluoride-containing artificial saliva: An in vitro study

    Directory of Open Access Journals (Sweden)

    Venith Jojee Pulikkottil

    2016-01-01

    Full Text Available Objective: (1 To evaluate the corrosion resistance of four different orthodontic archwires and to determine the effect of 0.5% NaF (simulating high fluoride-containing toothpaste of about 2250 ppm on corrosion resistance of these archwires. (2 To assess whether surface roughness (Ra is the primary factor influencing the corrosion resistance of these archwires. Materials and Methods: Four different archwires (stainless steel [SS], nickel-titanium [NiTi], titanium molybdenum alloy [TMA], and ion-implanted TMA were considered for this study. Surface characteristics were analyzed using scanning electron microscopy, atomic force microscopy (AFM, and energy dispersive spectroscopy. Linear polarization test, a fast electrochemical technique, was used to evaluate the corrosion resistance, in terms of polarization resistance of four different archwires in artificial saliva with NaF concentrations of 0% and 0.5%. Statistical analysis was performed by one-way analysis of variance. Results: The potentiostatic study reveals that the corrosion resistance of low-friction TMA (L-TMA > TMA > NiTi > SS. AFM analysis showed the surface Ra of TMA > NiTi > L-TMA > SS. This indicates that the chemical composition of the wire is the primary influential factor to have high corrosion resistance and surface Ra is only secondary. The corrosion resistance of all wires had reduced significantly in 0.5% acidic fluoride-containing artificial saliva due to formation of fluoride complex compound. Conclusion: The presence of 0.5% NaF in artificial saliva was detrimental to the corrosion resistance of the orthodontic archwires. Therefore, complete removal of residual high-fluorinated toothpastes from the crevice between archwire and bracket during tooth brushing is mandatory.

  6. Corrosion resistance of stainless steel, nickel-titanium, titanium molybdenum alloy, and ion-implanted titanium molybdenum alloy archwires in acidic fluoride-containing artificial saliva: An in vitro study

    Science.gov (United States)

    Pulikkottil, Venith Jojee; Chidambaram, S.; Bejoy, P. U.; Femin, P. K.; Paul, Parson; Rishad, Mohamed

    2016-01-01

    Objective: (1) To evaluate the corrosion resistance of four different orthodontic archwires and to determine the effect of 0.5% NaF (simulating high fluoride-containing toothpaste of about 2250 ppm) on corrosion resistance of these archwires. (2) To assess whether surface roughness (Ra) is the primary factor influencing the corrosion resistance of these archwires. Materials and Methods: Four different archwires (stainless steel [SS], nickel-titanium [NiTi], titanium molybdenum alloy [TMA], and ion-implanted TMA) were considered for this study. Surface characteristics were analyzed using scanning electron microscopy, atomic force microscopy (AFM), and energy dispersive spectroscopy. Linear polarization test, a fast electrochemical technique, was used to evaluate the corrosion resistance, in terms of polarization resistance of four different archwires in artificial saliva with NaF concentrations of 0% and 0.5%. Statistical analysis was performed by one-way analysis of variance. Results: The potentiostatic study reveals that the corrosion resistance of low-friction TMA (L-TMA) > TMA > NiTi > SS. AFM analysis showed the surface Ra of TMA > NiTi > L-TMA > SS. This indicates that the chemical composition of the wire is the primary influential factor to have high corrosion resistance and surface Ra is only secondary. The corrosion resistance of all wires had reduced significantly in 0.5% acidic fluoride-containing artificial saliva due to formation of fluoride complex compound. Conclusion: The presence of 0.5% NaF in artificial saliva was detrimental to the corrosion resistance of the orthodontic archwires. Therefore, complete removal of residual high-fluorinated toothpastes from the crevice between archwire and bracket during tooth brushing is mandatory. PMID:27829756

  7. Radiotracer studies on calcium ion-selective electrode membranes based on poly(vinyl chloride) matrices.

    Science.gov (United States)

    Craggs, A; Moody, G J; Thomas, J D; Willcox, A

    Radiotracer studies with (45)Ca and (36)Cl demonstrate that PVC matrix membranes containing Orion 92-20-02 liquid calcium ion-exchanger are permselective to counter-cations. Diffusion coefficients are quoted for the migration of (45)Ca between pairs of calcium solutions and are discussed in terms of solution concentration, membrane thickness and concentration level of sensor in the membrane. Migration of calcium ions from calcium chloride solution to a Group (II) metal chloride solution through a PVC membrane containing calcium liquid ion-exchanger is discussed in terms of solvent extraction and electrode selectivity coefficient parameters. Thus, magnesium, strontium and barium ions appear to inhibit migration through the membrane by their low affinity for the membrane liquid ion-exchanger sites, while the inhibition by beryllium ions is attributed to site blockage by the strong affinity of dialkylphosphate sites for beryllium.

  8. Selective retention of basic compounds by metal aquo-ion affinity chromatography.

    Science.gov (United States)

    Asakawa, Yoshiki; Yamamoto, Eiichi; Asakawa, Naoki

    2014-10-01

    A novel metal aquo-ion affinity chromatography has been developed for the analysis of basic compounds using heat-treated silica gel containing hydrated metal cations (metal aquo-ions) as the packing material. The packing materials of the metal aquo-ion affinity chromatography were prepared by the immobilization of a single metal component such as Fe(III), Al(III), Ag(I), and Ni(II) on silica gel followed by extensive heat treatment. The immobilized metals form aquo-ions to present cation-exchange ability for basic analytes and the cation-exchange ability for basic analytes depends on pKa of the immobilized metal species. In the present study, to evaluate the retention characteristics of metal aquo-ion affinity chromatography, the on-line solid-phase extraction of drugs was investigated. Obtained data clearly evidence the selective retention capability of metal aquo-ion affinity chromatography for basic analytes with sufficient capacity.

  9. Correlation among fluoride and metals in irrigation water and soils of Ethiopian Rift Valley

    Directory of Open Access Journals (Sweden)

    Elias Gizaw

    2014-05-01

    Full Text Available The levels of fluoride and selected metals in Ethiopian Rift Valley soils and irrigation water in the nearby sources were determined by fluoride ion selective electrode and flame atomic absorption spectrophotometer, respectively. The pH, conductivity, salinity and total dissolved solids in water and soil samples were also determined. Accuracy of the optimized procedure was evaluated using standard addition (spiking method and an acceptable percentage recovery was obtained. The fluoride concentrations in water samples were found in the range of 0.14-8.0 mg/L which is below the WHO limit of fluoride concentration for irrigation (less than 10 mg/L. The water soluble and total fluorides in soil were 2.3-16 µg/g and 209-1210 µg/g, respectively and are within the ranges recommended by FAO and WHO. The range of metal concentration in soil samples (µg/g dry weight basis and in water samples (mg/L respectively were: Na (684-6703, 8.6-67, Mg (1608-11229, 23-67, K (1776-4394, 1.1-20, Ca (7547-22998, 17-267, Cr (9.8-79, 0.07-0.17, Mn (143-700, 0.05-37, Co (50-112, 0.35-1.5, Ni (446-1288, 0.27-41, Fe (12180-32681, 6.0-48, Cu (8.9-45, 0.09-0.25 and Zn (31-89, 0.14-0.56. Fluoride was found to have significant correlation with major trace metals (Fe, Cu and Cr, but the correlation with other trace metals was not significant. DOI: http://dx.doi.org/10.4314/bcse.v28i2.7

  10. Synthetic Channel-forming Peptides and Ion Selectivity

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Introduction Peptides made up of alternating L- and D- amino acids can form β-helices as in gramicidin A or cyclic peptides that aggregate to form tubes[1]. In both cases the structures are hollow with all the side chains projecting outwards. Kennedy et al. [2] postulated that peptides having the (LLLD)n configuration could form helices with every fourth side chain projecting inward.It is a fact that synthetic N-formyl-( LeuSerLeuGly)6-OH, when added to a lipid bilayer, dimerizes, to form ion channels having conductances greater than that of gramicidin.

  11. Polarographic determination of fluoride using the adsorption wave of the Ce(III)-alizarin complexone-fluoride complex.

    Science.gov (United States)

    Guanghan, L; Xiaoming, L; Zhike, H; Shuanglong, H

    1991-09-01

    A very sensitive electrochemical method for trace measurement of fluoride in water is discussed. The complex of cerium(III) with alizarin complexone (ALC) and fluoride ion is adsorbed at the dropping mercury electrode. In cathodic sweeps, the peak height is directly proportional to the concentration of fluoride over the range 8 x 10(-8)-5 x 10(-6)M (1.5 x 10(-9)-9.5 x 10(-8) g/ml), and the detection limit is 5 x 10(-8)M (9.5 x 10(-10) g/ml). The proposed method was applied to the determination of fluoride in water.

  12. Fluoride glass fiber optics

    CERN Document Server

    Aggarwal, Ishwar D

    1991-01-01

    Fluoride Glass Fiber Optics reviews the fundamental aspects of fluoride glasses. This book is divided into nine chapters. Chapter 1 discusses the wide range of fluoride glasses with an emphasis on fluorozirconate-based compositions. The structure of simple fluoride systems, such as BaF2 binary glass is elaborated in Chapter 2. The third chapter covers the intrinsic transparency of fluoride glasses from the UV to the IR, with particular emphasis on the multiphonon edge and electronic edge. The next three chapters are devoted to ultra-low loss optical fibers, reviewing methods for purifying and

  13. Energetics of ion competition in the DEKA selectivity filter of neuronal sodium channels

    Directory of Open Access Journals (Sweden)

    D. Boda

    2015-03-01

    Full Text Available The energetics of ionic selectivity in the neuronal sodium channels is studied. A simple model constructed for the selectivity filter of the channel is used. The selectivity filter of this channel type contains aspartate (D, glutamate (E, lysine (K, and alanine (A residues (the DEKA locus. We use Grand Canonical Monte Carlo simulations to compute equilibrium binding selectivity in the selectivity filter and to obtain various terms of the excess chemical potential from a particle insertion procedure based on Widom's method. We show that K+ ions in competition with Na+ are efficiently excluded from the selectivity filter due to entropic hard sphere exclusion. The dielectric constant of protein has no effect on this selectivity. Ca2+ ions, on the other hand, are excluded from the filter due to a free energetic penalty which is enhanced by the low dielectric constant of protein.

  14. Anionic chromogenic chemosensors highly selective for fluoride or cyanide based on 4-(4-Nitrobenzylideneamine)phenol

    Energy Technology Data Exchange (ETDEWEB)

    Nicoleti, Celso R.; Marini, Vanderleia G.; Zimmermann, Lizandra M.; Machado, Vanderlei G., E-mail: vanderlei.machado@ufsc.br [Departamento de Quimica, Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2012-08-15

    4-(4-Nitrobenzylideneamine)phenol was used in two strategies allowing the highly selective detection of F{sup -} and CN{sup -}. Firstly, the compound in acetonitrile acts as a chromogenic chemosensor based on the idea that more basic anions cause its deprotonation (colorless solution), generating a colored solution containing phenolate. The discrimination of CN{sup -} over F{sup -} was obtained by adding 1.4% water to acetonitrile: water preferentially solvates F{sup -}, leaving the CN{sup -} free to deprotonate the compound. Another strategy involved an assay comprised of the competition between phenolate dye and the analyte for calyx[4]pyrrole in acetonitrile, a receptor highly selective for F{sup -}. Phenolate and calyx[4]pyrrole form a hydrogen-bonded complex, which changes the color of the medium. On the addition of various anions, only F{sup -} was able to restore the original color corresponding to phenolate in solution due to the fact that the anion dislodges phenolate from the complexation site. (author)

  15. Potential application of microporous structured poly(vinylidene fluoride-hexafluoropropylene)/poly(ethylene terephthalate) composite nonwoven separators to high-voltage and high-power lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hyun-Seok; Choi, Eun-Sun [Department of Chemical Engineering, Kangwon National University, Chuncheon, Kangwondo, 200-701 (Korea, Republic of); Kim, Jong Hun [Batteries R and D, LG Chem, Yusong-gu, Daejon, 305-380 (Korea, Republic of); Lee, Sang-Young, E-mail: syleek@kangwon.ac.kr [Department of Chemical Engineering, Kangwon National University, Chuncheon, Kangwondo, 200-701 (Korea, Republic of)

    2011-05-30

    Highlights: > Microporous-structured PVdF-HFP/PET composite nonwoven separators for Li-batteries. > Well-developed microporous structure and liquid electrolyte wettability. > Provision of facile ion transport and suppressed growth of cell impedance. > Superior cell performance at high-voltages/high-current densities. - Abstract: We demonstrate potential application of a new composite non-woven separator, which is comprised of a phase inversion-controlled, microporous polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) gel polymer electrolyte and a polyethylene terephthalate (PET) non-woven support, to high-voltage and high-power lithium-ion batteries. In comparison to a commercialized polyethylene (PE) separator, the composite non-woven separator exhibits distinct improvements in microporous structure and liquid electrolyte wettability. Based on the understanding of the composite non-woven separator, cell performances of the separator at challenging charge/discharge conditions are investigated and discussed in terms of ion transport of the separator and AC impedance of the cell. The aforementioned advantageous features of the composite non-woven separator play a key role in providing facile ion transport and suppressing growth of cell impedance during cycling, which in turn contribute to superior cell performances at harsh charge/discharge conditions such as high voltages and high current densities.

  16. A simple and colorimetric fluoride receptor and its fluoride-responsive organogel

    Energy Technology Data Exchange (ETDEWEB)

    Yu Xudong, E-mail: 081022009@fudan.edu.cn [College of Science, Hebei University of Science and Technology, Yuhua Road 70, Shijiazhuang 050080 (China); Li Yajuan [College of Science, Hebei University of Science and Technology, Yuhua Road 70, Shijiazhuang 050080 (China); Yin Yaobing; Yu Decai [College of Science, Hebei University of Engineering, 199 South street of Guangming, Handan 056038 (China)

    2012-08-01

    In this paper, a new p-nitrophenylhydrozine-based anion receptor 1 containing cholesterol group had been designed and synthesized. It could selectively recognize fluoride among different anions tested with color changes from pale yellow to red for visual detection. Simultaneously, it could gel in cyclohexane, and the gel was also fluoride-responsive. When treated with TBAF (tetra-n-butylammonium fluoride), the gel could undergo gel-sol transition accompanied by color, morphology and surface changes. The binding mechanism had been investigated by UV-vis and {sup 1}HNMR (proton nuclear magnetic resonance spectra) titrations. From SEM (scanning electron microscope), SAXS (small-angle X-ray scattering), IR (Infrared Spectroscopy) and CA (contact angle) experiments, it was indicated that the addition of F{sup -} could destroy the molecule assembly of host 1 in the gel state, thus resulting in the gel-to-sol transition due to the binding site competition effect. To the best of our knowledge, this was the simplest fluoride-responsive organogel with high selectivity. Highlights: Black-Right-Pointing-Pointer A novel kind receptor for selective recognition of fluoride had been designed. Black-Right-Pointing-Pointer Its organogel was also fluoride-responsive. Black-Right-Pointing-Pointer This is the simplest fluoride-responsive organogel with high selectivity.

  17. Integrated ion imprinted polymers-paper composites for selective and sensitive detection of Cd(II) ions

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Kai [State Key Laboratory of Environment Health - Incubation, Key Laboratory of Environment and Health, Ministry of Education, Key Laboratory of Environment and Health Wuhan, Ministry of Environmental Protection, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, #13 Hangkong Road, Hubei, 430030, Wuhan (China); Chen, Ying [Hubei Center for Disease Control and Prevention, No. 6 ZhuoDao Quan North Road, 430079, Wuhan (China); Zhou, Feng [State Key Laboratory of Environment Health - Incubation, Key Laboratory of Environment and Health, Ministry of Education, Key Laboratory of Environment and Health Wuhan, Ministry of Environmental Protection, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, #13 Hangkong Road, Hubei, 430030, Wuhan (China); Zhao, Xiaoya [Hubei Entry-Exit Inspection and Quarantine Bureau of PRC, No.588 Qingtaidadao Road, Hubei, 430022, Wuhan (China); Liu, Jiafa [Hubei Center for Disease Control and Prevention, No. 6 ZhuoDao Quan North Road, 430079, Wuhan (China); Mei, Surong; Zhou, Yikai [State Key Laboratory of Environment Health - Incubation, Key Laboratory of Environment and Health, Ministry of Education, Key Laboratory of Environment and Health Wuhan, Ministry of Environmental Protection, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, #13 Hangkong Road, Hubei, 430030, Wuhan (China); Jing, Tao, E-mail: jingtao@hust.edu.cn [State Key Laboratory of Environment Health - Incubation, Key Laboratory of Environment and Health, Ministry of Education, Key Laboratory of Environment and Health Wuhan, Ministry of Environmental Protection, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, #13 Hangkong Road, Hubei, 430030, Wuhan (China)

    2017-07-05

    Highlights: • IIPs are first grafted on the low-cost A4 print paper to develop an integrated paper-based device. • As an imprinted composite, the adsorption capacity is 155.2 mg g{sup –1} and the imprinted factor is more than 3.0. • As an analytical method, the limit of detection is 0.4 ng mL{sup –1}. • Based on the water quality standards, it could be used to determine Cd(II) ions in drinking water. - Abstract: Paper-based sensor is a new alternative technology to develop a portable, low-cost, and rapid analysis system in environmental chemistry. In this study, ion imprinted polymers (IIPs) using cadmium ions as the template were directly grafted on the surface of low-cost print paper based on the reversible addition-fragmentation chain transfer polymerization. It can be applied as a recognition element to selectively capture the target ions in the complex samples. The maximum adsorption capacity of IIPs composites was 155.2 mg g{sup –1} and the imprinted factor was more than 3.0. Then, IIPs-paper platform could be also applied as a detection element for highly selective and sensitive detection of Cd(II) ions without complex sample pretreatment and expensive instrument, due to the selective recognition, formation of dithizone-cadmium complexes and light transmission ability. Under the optimized condition, the linear range was changed from 1 to 100 ng mL{sup –1} and the limit of detection was 0.4 ng mL{sup –1}. The results were in good agreement with the classic ICP-MS method. Furthermore, the proposed method can also be developed for detection of other heavy metals by designing of new IIPs.

  18. Development of a disposable mercury ion-selective optode based on trityl-picolinamide as ionophore

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman,; Dam, Henk H.; Reinhoudt, David N.; Verboom, Willem

    2007-01-01

    A disposable ion-selective optode for mercury based on trityl-picolinamide (T-Pico) as neutral ionophore was developed. The sensing layer consist of plasticised PVC incorporating T-Pico as a selective ionophore for Hg2+, ETH 5418 as a chromoionophore, and potassium tetrakis[3,5-bis(trifluoromethyl)p

  19. Development of a disposable mercury ion-selective optode based on tritylpicolinamide as ionophore

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman, [Unknown; Dam, H.H.; Reinhoudt, David; Verboom, Willem

    2007-01-01

    A disposable ion-selective optode for mercury based on trityl-picolinamide (T-Pico) as neutral ionophore was developed. The sensing layer consist of plasticised PVC incorporating T-Pico as a selective ionophore for Hg2+, ETH 5418 as a chromoionophore, and potassium

  20. Soluble fluoride levels in drinking water-a major risk factor of dental fluorosis among children in Bongo community of Ghana.

    Science.gov (United States)

    Firempong, Ck; Nsiah, K; Awunyo-Vitor, D; Dongsogo, J

    2013-03-01

    The purpose of the study was to investigate the relationship between fluoride ions in drinking water and the incidence of dental fluorosis in some endemic areas of Bongo District, Ghana. Two hundred children were randomly selected from various homes and taken through a questionnaire. Their teeth were examined for the detection of dental fluorosis using the Dean's specific index. Samples of their permanent sources of water were taken for the determination of soluble fluoride levels by SPADNS spectrophotometric method. The study revealed that the incidence of dental fluorosis among the children in the main Bongo township was 63.0%, whereas villages outside the township recorded less than 10.0%. The respondents from the various communities had similar age group, educational background, sources of drinking water, oral hygiene habits and usage of oral health products, p-value > 0.05. However, there were statistically significant differences in the cases of dental fluorosis and fluoride ions among the communities, p-value dental fluorosis and the other characteristics, except the age group and fluoride ion concentration of the area. These findings strongly support the association between the dental fluorosis and the high fluoride levels in the underground water of Bongo community. Therefore, policy makers need to consider an alternative source of drinking water for the area.

  1. Mercury(II) ion-selective electrodes based on heterocyclic systems.

    Science.gov (United States)

    Mahajan, Rakesh Kumar; Sood, Pallavi; Pal Mahajan, Mohinder; Marwaha, Alka

    2007-09-01

    Mercury ion-selective electrodes (ISEs) were prepared with a polymeric membrane based on heterocyclic systems: 2-methylsulfanyl-4-(4-nitro-phenyl)-l-p-tolyl-1H-imidazole (I) and 2,4-diphenyl-l-p-tolyl-1H-imidazole (II) as the ionophores. Several ISEs were conditioned and tested for the selection of common ions. The electrodes based on these ionophores showed a good potentiometric response for Hg2+ ions over a wide concentration range of 5.0 x 10(5-) - 1.0 x 10(-1)M with near-Nernstian slopes. Stable potentiometric signals were obtained within a short time period of 20 s. The detection limits, the working pH range of the electrodes were 1.0 x 10(-5) M and 1.6-4.4 respectively. The electrodes showed better selectivity for Hg2+ ions over many of the alkali, alkaline-earth and heavy metal ions. Also sharp end points were obtained when these sensors were used as indicator electrodes for the potentiometric titration of Hg2+ ions with iodide ions.

  2. New Proton-Ionizable, Calixarene-Based Ligands for Selective Metal Ion Separations

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, Richard A.

    2012-06-04

    The project objective was the discovery of new ligands for performing metal ion separations. The research effort entailed the preparation of new metal ion complexing agents and polymers and their evaluation in metal ion separation processes of solvent extraction, synthetic liquid membrane transport, and sorption. Structural variations in acyclic, cyclic, and bicyclic organic ligands were used to probe their influence upon the efficiency and selectivity with which metal ion separations can be performed. A unifying feature of the ligand structures is the presence of one (or more) side arm with a pendent acidic function. When a metal ion is complexed within the central cavity of the ligand, ionization of the side arm(s) produces the requisite anion(s) for formation of an overall electroneutral complex. This markedly enhances extraction/transport efficiency for separations in which movement of aqueous phase anions of chloride, nitrate, or sulfate into an organic medium would be required. Through systematic structural variations, new ligands have been developed for efficient and selective separations of monovalent metal ions (e.g., alkali metal, silver, and thallium cations) and of divalent metal ion species (e.g., alkaline earth metal, lead, and mercury cations). Research results obtained in these fundamental investigations provide important insight for the design and development of ligands suitable for practical metal ion separation applications.

  3. Bilayer lipid membrane (BLM) based ion selective electrodes at the meso-, micro-, and nano-scales.

    Science.gov (United States)

    Liu, Bingwen; Rieck, Daniel; Van Wie, Bernard J; Cheng, Gary J; Moffett, David F; Kidwell, David A

    2009-03-15

    This paper presents a novel method for making micron-sized apertures with tapered sidewalls and nano-sized apertures. Their use in bilayer lipid membrane-based ion selective electrode design is demonstrated and compared to mesoscale bilayers and traditional PVC ion selective electrodes. Micron-sized apertures are fabricated in SU-8 photoresist films and vary in diameter from 10 to 40 microm. The tapered edges in SU-8 films are desired to enhance bilayer lipid membrane (BLM) formation and are fabricated by UV-light overexposure. Nano-apertures are made in boron diffused silicon film. The membranes are used as septa to separate two potassium chloride solutions of different concentrations. Lecithin BLMs are assembled on the apertures by ejecting lipid solution. Potassium ionophore, dibenzo-18-crown-6, is incorporated into BLMs by dissolving it in the lipid solution before membrane assembly. Voltage changes with increasing potassium ion concentrations are recorded with an A/D converter. Various ionophore concentrations in BLMs are investigated. At least a 1% concentration is needed for consistent slopes. Electrode response curves are linear over the 10(-6) to 0.1M range with a sub-Nernstian slope of 20mV per Log concentration change. This system shows high selectivity to potassium ions over potential interfering sodium ions. BLMs on the three different aperture sizes at the meso-, micro-, and nano-scales all show similar linear ranges and limits of detection (LODs) as PVC ion selective membranes.

  4. High fluoride water in Bondo-Rarieda area of Siaya County, Kenya: a hydro-geological implication on public health in the Lake Victoria Basin

    Science.gov (United States)

    2014-01-01

    Background Only a few studies to evaluate groundwater fluoride in Eastern Africa have been undertaken outside the volcanic belt of the Great Eastern Africa Rift Valley. The extent and impact of water fluoride outside these regions therefore remain unclear. The current study evaluated fluoride levels in household water sources in Bondo-Rarieda Area in the Kenyan part of the Lake Victoria Basin (LVB) and highlighted the risk posed by water fluoride to the resident communities. The results, it was anticipated, will contribute to in-depth understanding of the fluoride problem in the region. Methods A total of 128 water samples were collected from different water sources from the entire study area and analyzed for fluoride content using ion-selective electrodes. Results Lake Victoria was the main water source in the area but dams and open pans (39.5%), boreholes and shallow wells (23.5%), and streams (18.5%) were the principal water sources outside walking distances from the lake. The overall mean fluoride content of the water exceeded recommended limits for drinking water. The mean water fluoride was highest in Uyoma (1.39±0.84 ppm), Nyang’oma (1.00±0.59 ppm) and Asembo (0.92±0.46 ppm) and lowest in Maranda Division (0.69±0.42 ppm). Ponds (1.41±0.82 ppm), springs (1.25±0.43 ppm), dams and open pans (0.96±0.79 ppm), and streams (0.95±0.41 ppm) had highest fluoride levels but lake and river water did not have elevated fluoride levels. Groundwater fluoride decreased with increasing distance from the lake indicating that water fluoride may have hydro-geologically been translocated into the region from geochemical sources outside the area. Conclusions Lake Victoria was the main water source for the residents of Bondo-Rarieda Area. Majority of in-land residents however used water from dams, open pans, boreholes, shallow wells, ponds and streams, which was generally saline and fluoridated. It was estimated that 36% of children living in this area, who

  5. Selected Ion Flow-Drift Tube Mass Spectrometry: Quantification of Volatile Compounds in Air and Breath.

    Science.gov (United States)

    Spesyvyi, Anatolii; Smith, David; Španěl, Patrik

    2015-12-15

    A selected ion flow-drift tube mass spectrometric analytical technique, SIFDT-MS, is described that extends the established selected ion flow tube mass spectrometry, SIFT-MS, by the inclusion of a static but variable E-field along the axis of the flow tube reactor in which the analytical ion-molecule chemistry occurs. The ion axial speed is increased in proportion to the reduced field strength E/N (N is the carrier gas number density), and the residence/reaction time, t, which is measured by Hadamard transform multiplexing, is correspondingly reduced. To ensure a proper understanding of the physics and ion chemistry underlying SIFDT-MS, ion diffusive loss to the walls of the flow-drift tube and the mobility of injected H3O(+) ions have been studied as a function of E/N. It is seen that the derived diffusion coefficient and mobility of H3O(+) ions are consistent with those previously reported. The rate coefficient has been determined at elevated E/N for the association reaction of the H3O(+) reagent ions with H2O molecules, which is the first step in the production of H3O(+)(H2O)1,2,3 reagent hydrate ions. The production of hydrated analyte ion was also experimentally investigated. The analytical performance of SIFDT-MS is demonstrated by the quantification of acetone and isoprene in exhaled breath. Finally, the essential features of SIFDT-MS and SIFT-MS are compared, notably pointing out that a much lower speed of the flow-drive pump is required for SIFDT-MS, which facilitates the development of smaller cost-effective analytical instruments for real time breath and fluid headspace analyses.

  6. Assessment of fluoride content in tropical surface soils used for crop ...

    African Journals Online (AJOL)

    use

    ... characteristics of the soil, for instance a Pearson correlations analysis ... A bar chart showing the pattern of fluoride in the selected communities. Table 2. Fluoride content ..... Survey, BGS Technical Report WC/95/43. Stevens DP, McLaughlin ...

  7. Parabens do not increase fluoride uptake by dental enamel

    Directory of Open Access Journals (Sweden)

    Vanessa Silva Tramontino

    2010-04-01

    Full Text Available Objective: To evaluate whether methylparaben and propylparaben, which present a similar chemical structure, increase fluoride uptake by demineralized dental enamel when present in buffered solutions. Methods: The study comprised an in vitro experiment using blocks of bovine dental enamel with artificial carious lesions. Enamel blocks were exposed to the following treatment (n=12: fluoride solution (200 ppm fluoride - control; solution containing fluoride and 13 mM methylparaben; solution containing fluoride and 13 mM propylparaben in 35% propylene glycol; solution containing fluoride in 35% propylene glycol. All solutions were buffered (0.01 M cacodilate and the pH was adjusted to 6.27. The blocks were exposed to the treatment solutions in the proportion of 2 ml per mm2 of exposed enamel area and fluoride formed was estimated after removing an enamel layer by acid etching. Fluoride extracted was determined by ion specific electrode and the amount of enamel removed was estimated by phosphorus analysis. ANOVA followed by Tukey’s test were used for statistical analysis, with significance level at 5%. Results: The dental blocks of treatment groups containing both parabens and the control group presented similar fluoride concentration in enamel and no statistical difference was observed among them (p>0.05. The dental blocks of treatment group containing fluoride and propylene glycol showed the lowest value of fluoride present in enamel, which was significantly different from the control and fluoride and methylparaben groups (p<0.05. Conclusion: Methyl and propylparaben in a buffered solution do not enhance fluoride uptake by demineralized dental enamel.

  8. Review of progresses on clinical applications of ion selective electrodes for electrolytic ion tests: from conventional ISEs to graphene-based ISEs

    Directory of Open Access Journals (Sweden)

    Rongguo Yan

    2016-10-01

    Full Text Available There exist several positively and negatively charged electrolytes or ions in human blood, urine, and other body fluids. Tests that measure the concentration of these ions in clinics are performed using a more affordable, portable, and disposable potentiometric sensing method with few sample volumes, which requires the use of ion-selective electrodes (ISEs and reference electrodes. This review summarily descriptively presents progressive developments and applications of ion selective electrodes in medical laboratory electrolytic ion tests, from conventional ISEs, solid-contact ISEs, carbon nanotube based ISEs, to graphene-based ISEs.

  9. Fabrication, calibration and evaluation of a phosphate ion-selective microelectrode

    Energy Technology Data Exchange (ETDEWEB)

    Wang, John J., E-mail: johnwang1974@gmail.co [University of Cincinnati, 12716 Ginger Wood Lane, Clarksburg, MD 20871 (United States); Bishop, Paul L. [Department of Civil and Environmental Engineering, PO Box 210071, University of Cincinnati, Cincinnati, OH 45221-0071 (United States)

    2010-12-15

    To conduct the micro-environment study of flocs in an enhanced biological phosphorus removal (EBPR) process, a phosphate ion-selective microelectrode was developed. The cobalt-based microelectrodes have tip diameters of 5-20 {mu}m and respond to all the three forms of phosphate ions, namely, H{sub 2}PO{sub 4}{sup -}, HPO{sub 4}{sup 2-}, and PO{sub 4}{sup 3-}. The calibration curve at pH 7.5 had a slope of 31.5 mV per decade change of concentration and a R{sup 2} value of 0.99. Other characteristics of this microelectrode, such as response time, interferences from pH, ion strength, DO and other anions were also evaluated. - This paper presents the first phosphate ion-selective microelectrode in the world used for micro-level phorphorus removal studies.

  10. Selective ion changes during spontaneous mitochondrial transients in intact astrocytes.

    Directory of Open Access Journals (Sweden)

    Guillaume Azarias

    Full Text Available The bioenergetic status of cells is tightly regulated by the activity of cytosolic enzymes and mitochondrial ATP production. To adapt their metabolism to cellular energy needs, mitochondria have been shown to exhibit changes in their ionic composition as the result of changes in cytosolic ion concentrations. Individual mitochondria also exhibit spontaneous changes in their electrical potential without altering those of neighboring mitochondria. We recently reported that individual mitochondria of intact astrocytes exhibit spontaneous transient increases in their Na(+ concentration. Here, we investigated whether the concentration of other ionic species were involved during mitochondrial transients. By combining fluorescence imaging methods, we performed a multiparameter study of spontaneous mitochondrial transients in intact resting astrocytes. We show that mitochondria exhibit coincident changes in their Na(+ concentration, electrical potential, matrix pH and mitochondrial reactive oxygen species production during a mitochondrial transient without involving detectable changes in their Ca(2+ concentration. Using widefield and total internal reflection fluorescence imaging, we found evidence for localized transient decreases in the free Mg(2+ concentration accompanying mitochondrial Na(+ spikes that could indicate an associated local and transient enrichment in the ATP concentration. Therefore, we propose a sequential model for mitochondrial transients involving a localized ATP microdomain that triggers a Na(+-mediated mitochondrial depolarization, transiently enhancing the activity of the mitochondrial respiratory chain. Our work provides a model describing ionic changes that could support a bidirectional cytosol-to-mitochondria ionic communication.

  11. Selective ion changes during spontaneous mitochondrial transients in intact astrocytes.

    Science.gov (United States)

    Azarias, Guillaume; Chatton, Jean-Yves

    2011-01-01

    The bioenergetic status of cells is tightly regulated by the activity of cytosolic enzymes and mitochondrial ATP production. To adapt their metabolism to cellular energy needs, mitochondria have been shown to exhibit changes in their ionic composition as the result of changes in cytosolic ion concentrations. Individual mitochondria also exhibit spontaneous changes in their electrical potential without altering those of neighboring mitochondria. We recently reported that individual mitochondria of intact astrocytes exhibit spontaneous transient increases in their Na(+) concentration. Here, we investigated whether the concentration of other ionic species were involved during mitochondrial transients. By combining fluorescence imaging methods, we performed a multiparameter study of spontaneous mitochondrial transients in intact resting astrocytes. We show that mitochondria exhibit coincident changes in their Na(+) concentration, electrical potential, matrix pH and mitochondrial reactive oxygen species production during a mitochondrial transient without involving detectable changes in their Ca(2+) concentration. Using widefield and total internal reflection fluorescence imaging, we found evidence for localized transient decreases in the free Mg(2+) concentration accompanying mitochondrial Na(+) spikes that could indicate an associated local and transient enrichment in the ATP concentration. Therefore, we propose a sequential model for mitochondrial transients involving a localized ATP microdomain that triggers a Na(+)-mediated mitochondrial depolarization, transiently enhancing the activity of the mitochondrial respiratory chain. Our work provides a model describing ionic changes that could support a bidirectional cytosol-to-mitochondria ionic communication.

  12. Removal of fluoride from water using aluminium containing compounds

    Institute of Scientific and Technical Information of China (English)

    M. Karthikeyan; K. P. Elango

    2009-01-01

    Batch adsorption studies were undertaken to assess the suitability of aluminium titanate (AT) and bismuth aluminate (BA) to remove fluoride ions from water.The effect of pH,dose of adsorbent,contact time,initial concentration,co-ions and temperature on fluoride removal efficiency were studied.The amounts of fluoride ions adsorbed,at 30℃ from 4 mg/L of fluoride ion solution,by AT and BA are 0.85 and 1.55 mg/g,respectively.The experimental data fitted well to the Freundlich and Langmuir isotherms.Thermodynamic parameters such as △H~0,△S~0 and △G~0 indicated that the removal of fluoride ions by AT is exothermic and non-spontaneous while that by BA is endothermic and spontaneous.Furrier transform infrared (FT-IR) analysis and X-ray diffraction (XRD) patterns of the adsorbent before and after adsorption indicated that fluoride ions are chemisorbed by these adsorbents.

  13. Selective removal of nitrate ion using a novel composite carbon electrode in capacitive deionization.

    Science.gov (United States)

    Kim, Yu-Jin; Choi, Jae-Hwan

    2012-11-15

    We fabricated nitrate-selective composite carbon electrodes (NSCCEs) for use in capacitive deionization to remove nitrate ions selectively from a solution containing a mixture of anions. The NSCCE was fabricated by coating the surface of a carbon electrode with the anion exchange resin, BHP55, after grinding the resin into fine powder. BHP55 is known to be selective for nitrate ions. We performed desalination experiments on a solution containing 5.0 mM NaCl and 2.0 mM NaNO(3) using the NSCCE system constructed with the fabricated electrode. The selective removal of nitrate in the NSCCE system was compared to a membrane capacitive deionization (MCDI) system constructed with ion exchange membranes and carbon electrodes. The total quantity of chloride and nitrate ions adsorbed onto the unit area of the electrode in the MCDI system was 25 mmol/m(2) at a cell potential of 1.0 V. The adsorption of nitrate ions was 8.3 mmol/m(2), accounting for 33% of the total. In contrast, the total anion adsorption in the NSCCE system was 34 mmol/m(2), 36% greater than the total anion adsorption of the MCDI system. The adsorption of nitrate ions was 19 mmol/m(2), 2.3-times greater than the adsorption in the MCDI system. These results showed that the ions were initially adsorbed by an electrostatic force, and the ion exchange reactions then occurred between the resin powder in the coated layer and the solution containing mixed anions.

  14. Novel salicylic acid-oriented thiourea-type receptors as colorimetric chemosensor: Synthesis, characterizations and selective naked-eye recognition properties

    Science.gov (United States)

    Li, Shaowei; Cao, Xiufang; Chen, Changshui; Ke, Shaoyong

    2012-10-01

    Based on the salicylic acid backbone, three highly sensitive and selective colorimetric chemosensors with an acylthiourea binding unit have been designed, synthesized and characterized. These chemosensors have been utilized for selective recognition of fluoride anions in dry DMSO solution by typical spectroscopic titration techniques. Furthermore, the obtained chemosensors AR1-3 have shown naked-eye sensitivity for detection of biologically important fluoride ion over other anions in solution.

  15. Selective ion exchange recovery of rare earth elements from uranium mining solutions

    Science.gov (United States)

    Rychkov, Vladimir N.; Kirillov, Evgeny V.; Kirillov, Sergey V.; Bunkov, Grigory M.; Mashkovtsev, Maxim A.; Botalov, Maxim S.; Semenishchev, Vladimir S.; Volkovich, Vladimir A.

    2016-09-01

    A comparative study of rare earth, ferric and aluminum ions ion exchange behavior on gel sulfonated p;olystyrene cation exchange resins depending on the degree of the matrix cross-linking and pH of the solution is presented. Selective ion exchange of REEs is possible at the pH range of 1.5-2.0 using strongly acidic cation exchange resins containing more than 8 % of DVB. The preliminary results of testing the efficiency of REEs recovery from the industrial uranium underground leaching solutions are also presented.

  16. Development of a fully integrated analysis system for ions based on ion-selective optodes and centrifugal microfluidics

    Science.gov (United States)

    Johnson, R. D.; Badr, I. H.; Barrett, G.; Lai, S.; Lu, Y.; Madou, M. J.; Bachas, L. G.; Daunert, S. (Principal Investigator)

    2001-01-01

    A fully integrated, miniaturized analysis system for ions based on a centrifugal microfluidics platform and ion-selective optode membranes is described. The microfluidic architecture is composed of channels, five solution reservoirs, a measuring chamber, and a waste reservoir manufactured onto a disk-shaped substrate of poly(methyl methacrylate). Ion-selective optode membranes, composed of plasticized poly(vinyl chloride) impregnated with an ionophore, a proton chromoionophore, and a lipophilic anionic additive, were cast, with a spin-on device, onto a support layer and then immobilized on the disk. Fluid propulsion is achieved by the centrifugal force that results from spinning the disk, while a system of valves is built onto the disk to control flow. These valves operate based on fluid properties and fluid/substrate interactions and are controlled by the angular frequency of rotation. With this system, we have been able to deliver calibrant solutions, washing buffers, or "test" solutions to the measuring chamber where the optode membrane is located. An analysis system based on a potassium-selective optode has been characterized. Results indicate that optodes immobilized on the platform demonstrate theoretical responses in an absorbance mode of measurement. Samples of unknown concentration can be quantified to within 3% error by fitting the response function for a given optode membrane using an acid (for measuring the signal for a fully protonated chromoionophore), a base (for fully deprotonated chromoionophore), and two standard solutions. Further, the ability to measure ion concentrations by employing one standard solution in conjunction with acid and base and with two standards alone were studied to delineate whether the current architecture could be simplified. Finally, the efficacy of incorporating washing steps into the calibration protocol was investigated.

  17. Highly selective fluorescent probe for the detection of tin (IV) Ion

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Leiming; Yang, Jing; Wang, Qiusheng, E-mail: wangqsh@tjut.edu.cn; Zeng, Lintao, E-mail: zlt1981@126.com

    2014-04-15

    A novel fluorescent compound, 7-diethylamino-3-(2'-(1H-imidazo[4,5-b]phenazine)yl)coumarin (DIPC), was synthesized and employed as a fluorescent probe for detecting tin (IV) ion. Upon addition of tin (IV) ion to the solution of DIPC in DMSO–water (9:1, v/v), DIPC exhibited a considerable red-shift in its absorption spectrum and a decrease in fluorescence intensity. These changes result from tin (IV) ion binding to carbonyl oxygen of coumarin and nitrogen of imidazole, reflecting an enhanced ICT process from N,N-diethylamino unit to imidazole unit. The tin (IV) ion selective response was clearly observed by the naked eye through color change. We also studied the bioimaging application of DIPC for detecting tin (IV) ion in Hela cells. And a significant decrease of the fluorescence from the intracellular area was observed. -- Highlights: • We synthesized a novel coumarin derivative (DIPC). • DIPC was used to detect tin (IV) ion selectively. • The detection process was studied upon UV–vis and fluorescence spectrum. • We studied the bioimaging application of DIPC for detecting Sn{sup 4+} ion in cells.

  18. Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon

    Energy Technology Data Exchange (ETDEWEB)

    Soto, Fernando A. [Department of Chemical Engineering, Texas A& M University, College Station TX 77843-3122 USA; Yan, Pengfei [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Engelhard, Mark H. [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Marzouk, Asma [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825 Doha Qatar; Wang, Chongmin [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Xu, Guiliang [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Chen, Zonghai [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Amine, Khalil [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Liu, Jun [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Sprenkle, Vincent L. [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; El-Mellouhi, Fedwa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825 Doha Qatar; Balbuena, Perla B. [Department of Chemical Engineering, Texas A& M University, College Station TX 77843-3122 USA; Li, Xiaolin [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA

    2017-03-07

    Solid-electrolyte interphase (SEI) films with controllable properties are highly desirable for improving battery performance. In this paper, a combined experimental and theoretical approach is used to study SEI films formed on hard carbon in Li- and Na-ion batteries. It is shown that a stable SEI layer can be designed by precycling an electrode in a desired Li- or Na-based electrolyte, and that ionic transport can be kinetically controlled. Selective Li- and Na-based SEI membranes are produced using Li- or Na-based electrolytes, respectively. The Na-based SEI allows easy transport of Li ions, while the Li-based SEI shuts off Na-ion transport. Na-ion storage can be manipulated by tuning the SEI layer with film-forming electrolyte additives, or by preforming an SEI layer on the electrode surface. The Na specific capacity can be controlled to < 25 mAh g(-1); approximate to 1/10 of the normal capacity (250 mAh g(-1)). Unusual selective/ preferential transport of Li ions is demonstrated by preforming an SEI layer on the electrode surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion-selective conductors using electrochemical approaches.

  19. Fluoride toothpastes and fluoride mouthrinses for home use

    OpenAIRE

    Andrew Rugg-Gunn; Jolan Bánóczy

    2013-01-01

    Objective. To provide a brief commentary review of fluoride-containing toothpastes and mouthrinses with emphasis on their use at home. Toothpastes and mouthrinses are just two of many ways of providing fluoride for the prevention of dental caries. The first investigations into incorporating fluoride into toothpastes and mouthrinses were reported in the middle 1940s. Unlike water fluoridation (which is ‘automatic fluoridation’), fluoride-containing toothpastes and fluoride-containing mouthrins...

  20. Exraction and separation of CERIUM(IV/FLUORINE in fluoride-bearing cerium sulfate solution with fluoride coordination agent

    Directory of Open Access Journals (Sweden)

    Y. Li

    2014-07-01

    Full Text Available In this paper the extraction and separation of cerium/fluorine in fluoride-bearing cerium sulfate solution with fluoride coordination agent has been studied. The UV-vis spectra suggest that Zr6+ and Al3+ can scrub the F- from [CeF2] 2+ complex. The separation and conductivity studies show that aluminum salt is the most suitable fluoride coordination agent, and an ion-exchange reaction is involved between Ce4+/ [CeF2] 2+ and hydrogen ion.

  1. Macrocyclic compound as ionophores in lead(Ⅱ)ion-selective electrodes with excellent response characteristics

    Institute of Scientific and Technical Information of China (English)

    HUANG MeiRong; MA XiaoLi; LI XinGui

    2008-01-01

    Macrocyclic compounds, such as crown ethers, azacrown ethers, thiacrown ethers, calixarenes and porphyrins, which act as ionophores in lead(Ⅱ) ion-selective electrodes, are systematically summarized based on the latest literatures. The molecular structure characteristics of the ionophores are general-ized. The modification regulations for the substituted ionophores are elaborated with the purpose ofimproving the response features of the lead(Ⅱ) ion-selective electrodes assembled by them. It is pointed out that the introduction of pendant moieties which contain soft base coordination centers like N, S and P atoms is in favor of adjusting the cavity size and conformation of the macrocyclic com-pounds. Furthermore, there is synergic effect between the cavity and the donor sites of the ligand and thus the selective complexation of lead ions is easily realized, resulting in significant avoidance of the interference from other metal ions. The macrocyclic ionophore having the best response characteris-tics thus far was found to be N,N'-dimethylcyanodiaza-18-crown-6 with the detection limit of 7.0×10-8 (14.5 μg/L), which is one of the uncommon ionophores that can really eliminate the interference from silver and mercury ions. The selectivity coefficients of the ionophore for lead ions over other metal ions, such as alkali, alkaline earth and transition metal ions are in the order of 10-4 or smaller, where the se-lectivity coefficient of lead(Ⅱ) over mercury(Ⅱ) ions is much lower, down to 8.9×10-4. The structure de-sign idea for high-performance ionophore is proposed according to present results. The incorporation of nitrogen atom, especially cyano group or thiocyano group or amino/imino groups, rather than thio atom alone could result in new excellent lead ionophores. The aborative design for metacyclophanes containing aromatic nitrogen atoms with the aim of creating excellent ionophores would also become a potential research trend. The lead(Ⅱ) ion-selective

  2. Reactions of Ions with Ionic Liquid Vapors by Selected-Ion Flow Tube Mass Spectrometry

    Science.gov (United States)

    2016-06-07

    spectrometric methods14 and, more recently, IR5,6 and UVvis spectroscopy.7 Indirect methods involve transpiration,8 effusion,9 or thermal gravimetric analyses... experimental mass peaks observed for EMIMþNTf2 are listed in Table 1, along with their enthalpies and free energies of reaction (at 298 K). In the cases...ion trio definitely shows the presence of neutral RTIL vapors in the flow tube. The calculated geometry of EMIMþNTf2 NH4 þ in Figure 3 shows a dramatic

  3. Highly selective and sensitive fluorescent chemosensor for femtomolar detection of silver ion in aqueous medium

    Directory of Open Access Journals (Sweden)

    Abraham Daniel Arulraj

    2015-12-01

    Full Text Available The chemical sensing for the trace level detection of silver ion in aqueous solution still remains a challenge using simple, rapid, and inexpensive method. We report that thionine can be used as a fluorescent probe for the detection of Ag+ ion. The successive addition of Ag+ ion to the solution containing thionine quenches (turns-off the fluorescence intensity of thionine. Association and quenching constants have been estimated by the Benesi–Hildebrand method and Stern–Volmer plot, respectively. From the plot, the nature of the fluorescence quenching was confirmed as static quenching. An important feature of our chemosensor is high selectivity towards the determination of silver ion in aqueous solution over the other competitive metal ions. The detection limit of the sensor achieved 5 fM for Ag+ ion, which is superior to all previously reported chemosensors. The NMR and FT-IR studies were also carried out to support the complex formation between thionine and Ag+ ion. The practicality of the proposed chemosensor for determination of Ag+ ion was carried in untreated water samples.

  4. Measurements of Ion Selective Containment on the RF Charge Breeder Device BRIC

    CERN Document Server

    Variale, Vincenzo; Batazova, Marina; Boggia, Antonio; Clauser, Tarcisio; Kuznetsov, Gennady I; Rainò, Antonio; Shiyankov, Sergey; Skarbo, Boris A; Valentino, Vincenzo; Verrone, Grazia

    2005-01-01

    The "charge state breeder" BRIC (BReeding Ion Charge) is based on an EBIS source and it is designed to accept Radioactive Ion Beam (RIB) with charge +1, in a slow injection mode, to increase their charge state up to +n. BRIC has been developed at the INFN section of Bari (Italy) during these last 3 years with very limited funds. Now, it has been assembled at the LNL (Italy) where are in progress the first tests as stand alone source. The new feature of BRIC, with respect to the classical EBIS, is given by the insertion, in the ion drift chamber, of a Radio Frequency (RF) Quadrupole aiming to filtering the unwanted elements and then making a more efficient containment of the wanted ions. In this contribution, the measurements of the selective effect on the ion charge state containement of the RF quadrupole field, applied on the ion chamber, will be reported and discussed. The ion charge state analisys of the ions trapped in BRIC seem confirm, as foreseen by simulation results carried out previously, that the s...

  5. A Change in the Ion Selectivity of Ligand-Gated Ion Channels Provides a Mechanism to Switch Behavior.

    Directory of Open Access Journals (Sweden)

    Jennifer K Pirri

    Full Text Available Behavioral output of neural networks depends on a delicate balance between excitatory and inhibitory synaptic connections. However, it is not known whether network formation and stability is constrained by the sign of synaptic connections between neurons within the network. Here we show that switching the sign of a synapse within a neural circuit can reverse the behavioral output. The inhibitory tyramine-gated chloride channel, LGC-55, induces head relaxation and inhibits forward locomotion during the Caenorhabditis elegans escape response. We switched the ion selectivity of an inhibitory LGC-55 anion channel to an excitatory LGC-55 cation channel. The engineered cation channel is properly trafficked in the native neural circuit and results in behavioral responses that are opposite to those produced by activation of the LGC-55 anion channel. Our findings indicate that switches in ion selectivity of ligand-gated ion channels (LGICs do not affect network connectivity or stability and may provide an evolutionary and a synthetic mechanism to change behavior.

  6. Fluoride and Oral Health.

    Science.gov (United States)

    O'Mullane, D M; Baez, R J; Jones, S; Lennon, M A; Petersen, P E; Rugg-Gunn, A J; Whelton, H; Whitford, G M

    2016-06-01

    The discovery during the first half of the 20th century of the link between natural fluoride, adjusted fluoride levels in drinking water and reduced dental caries prevalence proved to be a stimulus for worldwide on-going research into the role of fluoride in improving oral health. Epidemiological studies of fluoridation programmes have confirmed their safety and their effectiveness in controlling dental caries. Major advances in our knowledge of how fluoride impacts the caries process have led to the development, assessment of effectiveness and promotion of other fluoride vehicles including salt, milk, tablets, toothpaste, gels and varnishes. In 1993, the World Health Organization convened an Expert Committee to provide authoritative information on the role of fluorides in the promotion of oral health throughout the world (WHO TRS 846, 1994). This present publication is a revision of the original 1994 document, again using the expertise of researchers from the extensive fields of knowledge required to successfully implement complex interventions such as the use of fluorides to improve dental and oral health. Financial support for research into the development of these new fluoride strategies has come from many sources including government health departments as well as international and national grant agencies. In addition, the unique role which industry has played in the development, formulation, assessment of effectiveness and promotion of the various fluoride vehicles and strategies is noteworthy. This updated version of 'Fluoride and Oral Health' has adopted an evidence-based approach to its commentary on the different fluoride vehicles and strategies and also to its recommendations. In this regard, full account is taken of the many recent systematic reviews published in peer reviewed literature.

  7. Modification of zeolities with ammonium fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Rosinski, E.J.

    1988-05-17

    A method for enhancing the shape selectivity and adjusting catalytic activity of a crystalline zeolite, including a highly siliceous zeolite, is disclosed. Such a method involves contacting the zeolite with an ammonium fluoride solution in the absence of an aluminum source, optionally contacting the treated zeolite with a warm aqueous solution of an ammonium salt, and then calcining the fluoride and ammonium treated zeolite to produce a more shape selective zeolite material. Such treated zeolite are useful in catalysts which promote shape selective conversion of organic compounds including, for example, hydrocarbon cracking reactions.

  8. A method for producing controlled fluoride release from an orthodontic bracket.

    Science.gov (United States)

    Li, Song; Hobson, Ross S; Bai, Yuxing; Yan, Zhuoqun; Carrick, Thomas E; McCabe, John F

    2007-12-01

    The aim of this study was to manufacture and test, in vitro, a novel modification to provide fluoride-releasing orthodontic brackets. Thirty-two orthodontic brackets were drilled to produce a recess (approximately 1.3 mm in diameter and 0.7 mm in depth) at the centre of the bracket base. Four materials, with and without the addition of sodium fluoride, a glass ionomer cement (Ketac Cem micro), a resin-modified glass ionomer cement (RMGIC; GC Fuji Ortho LC), a zinc phosphate (Zinc Cement Improved), and a resin (Transbond XT) were used to fill the recess in the bracket base. Fluoride release was measured daily during the first week and then weekly for 10 weeks. An ion chromatograph with suppressed conductivity was used for free fluoride ion determination. Statistical analysis to determine the amount of flouride release was undertaken using analysis of variance and Tukey's test. During the first 2 weeks, the resin group, with the addition of 38 per cent sodium fluoride added, released significantly more free fluoride (P < 0.05), but after 2 weeks the fluoride release markedly decreased. After 5 weeks, the RMGIC group, with 15 per cent added sodium fluoride, had significantly higher (P < 0.05) daily fluoride release than the other groups. The findings demonstrated that an appropriate fluoridated material can be used as a fluoride-releasing reservoir in a modified orthodontic bracket to enable it to release fluoride over the period of fixed appliance treatment.

  9. Fissure seal or fluoride varnish?

    Science.gov (United States)

    Deery, Christopher

    2016-09-01

    Data sourcesCochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, the US National Institutes of Health Trials Register and the World Health Organization (WHO) Clinical Trials Registry PlatformStudy selectionRandomised controlled trials (RCTs) with at least 12 months follow-up, in which fissure sealants, or fissure sealants together with fluoride varnishes, were compared with fluoride varnishes alone for preventing caries in occlusal surfaces of permanent teeth of children and adolescents.Data extraction and synthesisTwo reviewers independently screened search results, extracted data and assessed risk of bias of included studies. Studies were grouped and analysed on the basis of sealant material type (resin-based sealant and glass ionomer-based sealant, glass ionomer and resin-modified glass ionomer) and different follow-up periods. Odds ratio were calculated for caries or no caries on occlusal surfaces of permanent molar teeth. Mean differences were calculated for continuous outcomes and data. Evidence quality was assessed using GRADE (Grades of Recommendation, Assessment, Development and Evaluation) methods.ResultsEight RCTs involving a total of 1747 children aged five to ten years of age were included. Three trials compared resin-based fissure sealant versus fluoride varnish. Results from two studies (358 children) after two years were combined. Sealants prevented more caries, pooled odds ratio (OR) = 0.69 (95%CI; 0.50 to 0.94). One trial with follow-up at four and nine years found that the caries-preventive benefit for sealants was maintained, with 26% of sealed teeth and 55.8% of varnished teeth having developed caries at nine years. Evidence for glass-ionomer sealants was of low quality. One split-mouth trial analysing 92 children at two-year follow-up found a significant difference in favour of resin-based fissure sealant together with fluoride varnish compared with fluoride varnish only (OR

  10. [Fluoride urinary excretion in Mexico City's preschool children].

    Science.gov (United States)

    Juárez-López, María Lilia Adriana; Hernández-Guerrero, Juan Carlos; Jiménez-Farfán, Dolores; Molina-Frechero, Nelly; Murrieta-Pruneda, Francisco; López-Jiménez, Georgina

    2008-01-01

    The assessment of urinary fluoride excretion during dental developing stage has been reported for different countries with community fluoride programs. Also, one of the factors that could influence on retention and excretion of fluoride is the deficient nutrition so the aim of this study was to determine fluoride urinary excretion by a group of preschool children with and without malnutrition. Urinary samples from 24 hours were collected from 60 preschool children selected by convenience from Iztapalapa area of Mexico City, 30 with malnutrition and 30 with standard nutritrional status by weight for age. The samples were analyzed by fluoride especific electrode. Orion 720A. The average concentration of fluoride in urine from preschool children with and without malnutrition were 0.89 +/- 0.4 mg/L and 0.80 +/- 0.3 mg/L, respectively. The mean of 24 hours total fluoride excreted were 367 +/- 150 microg/24 hrs. in malnutrition children and 355 +/- 169 microg/24 hrs. for those with standard nutritional status. There were no differences statistically significant between groups. The urinary fluoride excretion for children with and without malnutrition were in the optimal range of fluoridation for the prevention of caries decay. Malnutrition was no associated with changes on fluoride orine concentration and excretion rates.

  11. Electrochemical activation and inhibition of neuromuscular systems through modulation of ion concentrations with ion-selective membranes

    Science.gov (United States)

    Song, Yong-Ak; Melik, Rohat; Rabie, Amr N.; Ibrahim, Ahmed M. S.; Moses, David; Tan, Ara; Han, Jongyoon; Lin, Samuel J.

    2011-12-01

    Conventional functional electrical stimulation aims to restore functional motor activity of patients with disabilities resulting from spinal cord injury or neurological disorders. However, intervention with functional electrical stimulation in neurological diseases lacks an effective implantable method that suppresses unwanted nerve signals. We have developed an electrochemical method to activate and inhibit a nerve by electrically modulating ion concentrations in situ along the nerve. Using ion-selective membranes to achieve different excitability states of the nerve, we observe either a reduction of the electrical threshold for stimulation by up to approximately 40%, or voluntary, reversible inhibition of nerve signal propagation. This low-threshold electrochemical stimulation method is applicable in current implantable neuroprosthetic devices, whereas the on-demand nerve-blocking mechanism could offer effective clinical intervention in disease states caused by uncontrolled nerve activation, such as epilepsy and chronic pain syndromes.

  12. Fast spectrophotometric determination of fluoride in ground waters by flow injection using partial least-squares calibration

    Energy Technology Data Exchange (ETDEWEB)

    Arancibia, Juan A.; Rullo, Anabel; Olivieri, Alejandro C.; Di Nezio, Susana; Pistonesi, Marcelo; Lista, Adriana; Fernandez Band, Beatriz S

    2004-06-04

    The presence of sulphate constitutes a serious interference in the usual zirconium lake-based spectrophotometric method for the determination of fluoride in water. In this report, full spectral data have been recorded for the zirconium lake of 2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalene-disulfonate (SPADNS) in the simultaneous presence of fluoride and sulphate, as obtained with a flow injection system with a diode-array detector. The information has been processed with partial least-squares (PLS) multivariate calibration. Adequate modeling using a sixteen-sample calibration set allows fluoride to be determined in ground waters by the automated flow injection method, even in the presence of sulphate in concentrations up to 1000 mg l{sup -1}. In the calibration range 0-1.50 mg l{sup -1} for fluoride, the limit of detection is 0.1 mg l{sup -1}. The fluoride contents in real samples, as determined with the present method, were satisfactorily compared with those provided by ion selective potentiometry.

  13. CO2 laser and fluoride on the inhibition of root caries—an in vitro microbial model

    Science.gov (United States)

    Steiner-Oliveira, C.; Rodrigues, L. K. A.; Parisotto, T. M.; Sousa E Silva, C. M.; Hara, A. T.; Nobre-Dos-Santos, M.

    2010-09-01

    An increase in the dental caries prevalence on root surfaces has been observed mainly in elderly. This research assessed, in vitro, the effectiveness of a pulsed CO2 (λ = 10.6 μm) laser associated or not with fluoride, in reducing human root dentine demineralization in conditions that mimic an oral high cariogenic challenge. After sterilization, root dentine specimens were randomly assigned into 6 groups ( n = 30), in triplicate. The groups were Control (C), Streptococcus mutans (SM), Fluoride (F), Laser (L), Fluoride + laser (FL), and Laser + fluoride (LF). Except for the control group, all the specimens were inoculated with SM and immersed 3 times a day in a 40% sucrose bath. After a 7-day cariogenic challenge, the mineral loss and lesion depth were evaluated by transverse microradiography and fluoride in the biofilm was determined using an ion-selective electrode. Results were statistically analyzed by analysis of variance, at 5% of significance level. For groups C, SM, F, L, FL and LF, the means (standard-deviation) of mineral loss were 816.3 (552.5)a, 3291.5 (1476.2)c, 2508.5 (1240.5)bc, 2916.2 (1323.7)c, 1839.7 (815.2)b and 1955.0 (1001.4)b, respectively; while lesion depths were 39.6 (22.8)a, 103.1 (38.9)c, 90.3 (44.6)bc, 91.7 (27.0)bc, 73.3 (26.6)b, 75.1 (35.2)b, respectively (different superscript letters indicate significant differences among groups). In conclusion, irradiation of root dentine with a pulsed CO2 laser at fluency of 12.0 J/cm2 was able to inhibit root surface demineralization only when associated with fluoride. No synergy effect on the inhibition of root dentine mineral loss was provided by the combination of fluoride application and laser irradiation.

  14. Overcoming Pitfalls in Boundary Elements Calculations with Computer Simulations of Ion Selective Membrane Electrodes.

    Science.gov (United States)

    Yuan, Dajing; Bakker, Eric

    2017-08-01

    Finite difference analysis of ion-selective membranes is a valuable tool for understanding a range of time dependent phenomena such as response times, long and medium term potential drifts, determination of selectivity, and (re)conditioning kinetics. It is here shown that an established approach based on the diffusion layer model applied to an ion-exchange membrane fails to use mass transport to account for concentration changes at the membrane side of the phase boundary. Instead, such concentrations are imposed by the ion-exchange equilibrium condition, without taking into account the source of these ions. The limitation is illustrated with a super-Nernstian potential jump, where a membrane initially void of analyte ion is exposed to incremental concentrations of analyte in the sample. To overcome this limitation, the two boundary elements, one at either side of the sample-membrane interface, are treated here as a combined entity and its total concentration change is dictated by diffusional fluxes into and out of the interface. For each time step, the concentration distribution between the two boundary elements is then computed by ion-exchange theory. The resulting finite difference simulation is much more robust than the earlier model and gives a good correlation to experiments.

  15. Cell Adhesion Selectivity of Stent Material to improve Bio-functionality by Ion Beam Modification

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jaesang; Park, JUngchan; Jung, Myunghwan; Kim, Yongki [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Junkyu [Bio alpha., Co. Ltd., Gimhae (Korea, Republic of)

    2014-05-15

    In this study, ion implantation into collagen coated Co-Cr alloy, which is a cheaper material of the artificial stent product comparing with Ti alloy, has been studied to develop small diameter artificial stent by the cell adhesion control. The size of stent was 1.6mm of the diameter and 18mm of the length. The life-time of artificial stent depends on adhesion property of endothelial-cells. We successfully controlled cell adhesion selectivity between endothelial cell and muscle cell by using collagen coated and He{sup +} ion beam irradiated Co-Cr-alloy to apply to artificial stent. But, we did not achieve the inhibition of platelet adhesion, yet by using collagen coating and He{sup +} ion beam irradiation. Based on this study, we have plan to research about separation between collagen coating effect and ion beam effect. Also, we will have more detail analysis of the mechanism of cell attachment. In recent years, ion implantation has been applied to the surface modification of prosthesis to improve blood compatibility and tissue compatibility in field of biomedical application. As well known, bio compatibility was concerned with the cell adhesion selectivity for bio-functionality. The biomedical application of ion beam technology would be used more widely in the future such as catheter and artificial graft.

  16. Fluoride adsorption on goethite in relation to different types of surface sites

    NARCIS (Netherlands)

    Hiemstra, T.; Riemsdijk, van W.H.

    2000-01-01

    Metal (hydr)oxides have different types of surface groups. Fluoride ions have been used as a probe to assess the number of surface sites. We have studied the F− adsorption on goethite by measuring the F− and H interaction and F− adsorption isotherms. Fluoride ions exchange against singly coordinated

  17. Advances in flowing afterglow and selected-ion flow tube techniques

    Science.gov (United States)

    Squires, Robert R.

    1992-09-01

    New developments in flowing afterglow and selected-ion flow tube (SIFT) techniques are briefly reviewed. Particular emphasis is given to the new chemical and physical information that can be obtained with use of the tandem flowing afterglow-triple quadrupole apparatus developed in the author's laboratory. Several outstanding recent achievements in the design and utilization of flowing afterglow and SIFT instruments in other laboratories are briefly highlighted that illustrate the power and flexibility of flow-tube-based methods. These include isotope tracer experiments with the tandem flowing afterglow-SIFT instrument in Boulder, studies of large molecular cluster ions with the variable temperature facility at Penn State, and gas-phase metal ion reactions with the laser ablation/fast flow reactor in Madison. Recent applications of the flowing afterglow-triple quadrupole instrument in our laboratory have made use of collision-induced dissociation (CID) as a tool for synthesizing novel ions and for obtaining new thermo-chemical information from threshold energy measurements. Collision-induced decar☐ylation of organic car☐ylate ions provides access to a variety of unusual and highly basic carbanions that cannot be generated with conventional ion sources. The formation and properties of saturated alkyl ions and studies of gas-phase reactions of the methyl anion are briefly described. We have developed a new method for carrying out "preparative CID" in a flowing afterglow with use of a mini-drift tube; some recent applications of this new ion source are presented. Measurement of CID thresholds for simple cleavage reactions of thermalized ions can provide accurate measures of bond strengths, gas-phase acidities and basicities, and heats of formation for ions and reactive neutral species. Applications of this approach in the thermochemical characterization of carbenes, benzynes and biradicals are described. Future prospects for the continued development of flow

  18. Method for selective detection of explosives in mass spectrometer or ion mobility spectrometer at parts-per-quadrillion level

    Science.gov (United States)

    Ewing, Robert G.; Atkinson, David A.; Clowers, Brian H.

    2015-09-01

    A method for selective detection of volatile and non-volatile explosives in a mass spectrometer or ion mobility spectrometer at a parts-per-quadrillion level without preconcentration is disclosed. The method comprises the steps of ionizing a carrier gas with an ionization source to form reactant ions or reactant adduct ions comprising nitrate ions (NO.sub.3.sup.-); selectively reacting the reactant ions or reactant adduct ions with at least one volatile or non-volatile explosive analyte at a carrier gas pressure of at least about 100 Ton in a reaction region disposed between the ionization source and an ion detector, the reaction region having a length which provides a residence time (tr) for reactant ions therein of at least about 0.10 seconds, wherein the selective reaction yields product ions comprising reactant ions or reactant adduct ions that are selectively bound to the at least one explosive analyte when present therein; and detecting product ions with the ion detector to determine presence or absence of the at least one explosive analyte.

  19. On the origin of ion selectivity in the Cys-loop receptor family.

    Science.gov (United States)

    Sine, Steven M; Wang, Hai-Long; Hansen, Scott; Taylor, Palmer

    2010-01-01

    Agonist binding to Cys-loop receptors promotes a large transmembrane ion flux of several million cations or anions per second. To investigate structural bases for the dynamics (MD) simulations, X-ray crystallography, and single channel recording. MD simulations of the muscle nicotinic receptor, imbedded in a lipid bilayer with an applied transmembrane potential, reveal single cation translocation events during transient periods of channel hydration. During the simulation trajectory, cations paused for prolonged periods near several rings of anionic residues projecting from the lumen of the extracellular domain of the receptor, but subsequently the cation moved rapidly through the hydrophobic transmembrane region as the constituent alpha-helices exhibited back and forth rocking motions. Cocrystallization of acetylcholine binding protein with sulfate ions revealed coordination of five sulfates with residues from one of these charged rings; in cation-selective Cys-loop receptors this ring contains negatively charged residues, whereas in anion-selective receptors it contains positively charged residues. In the muscle nicotinic receptor, charge reversal of residues of this ring decreases unitary conductance by up to 80%. Thus in Cys-loop receptors, a series of charged rings along the ion translocation pathway concentrates hydrated ions relative to bulk solution, giving rise to charge selectivity, and then subtle motions of the hydrophobic transmembrane, coupled with transient periods of water filling, enable rapid ion flux.

  20. Fluoride and bacterial content of bottled drinking water versus municipal tap water

    Directory of Open Access Journals (Sweden)

    Mythri H

    2010-01-01

    Full Text Available Background: Water is a divine gift. People quench their thirst without questioning the source of water. But, apprehension about contaminants in municipal water supplies along with increased fear of fluorosis made bottled drinking water as one of the important tradable commodities. Objectives: The objectives of the study were to determine and compare the fluoride and bacterial contents of commercially available bottled drinking water and municipal tap water in Davangere city, Karnataka. Materials and Methods: Fifty samples of 10 categories of bottled drinking water with different batch numbers were purchased and municipal water from different sources were collected. Fluoride levels were determined by an ion-selective electrode. Water was cultured quantitatively and levels of bacteria were calculated as colony-forming units (CFUs per milliliter. Results: Descriptive analysis of water samples for fluoride concentration was in the range of 0.07-0.33 for bottled drinking water, Bisleri showing the highest of 0.33. A comparison of the mean values of microbial count for bottled drinking water with that of municipal tap water showed no statistically significant difference, but was more than the standard levels along with the presence of fungus and maggots. Conclusion: The fluoride concentration was below the optimal level for both municipal tap water and bottled drinking water. CFUs were more than the recommended level in both municipal tap water and bottled drinking water.

  1. Ion-selective electrodes with solid contact for heavy metals determination

    OpenAIRE

    2013-01-01

    Potentiometric properties of ion-selective electrodes with solid contact for lead, cadmium and zinc determination were investigated. The ionic liquids (ILs) alkyl methyl imidazolium chlorides are used as lipophilic ionic additive to the membrane phase and as transducer media. The basic analytical parameters of the studied electrodes, such as the slope characteristic, the detection limit, response time, lifetime, selectivity coefficients against various inorganic cations as well as the depende...

  2. Liquid membrane ion-selective electrodes for potentiometric dosage of coper and nickel

    Directory of Open Access Journals (Sweden)

    MARIA PLENICEANY

    2005-02-01

    Full Text Available This paper presents experimental and theoretical data regarding the preparation and characterization of three liquid-membrane electrodes, which have not been mentioned in the specialized literature so far. The active substances, the solutions of which in nitrobenzene formed the membranes on a graphite rod, are simple complex combinations of Cu(II and Ni(II ions with an organic ligand belonging to the Schiff base class: N-[2-thienylmethilidene]-2-aminoethanol (TNAHE. The Cu2+ -selective and Ni2+ -selective electrodes were used to determine the copper and nickel ions in aqueous solutions, both by direct potentiometry and by potentiometric titration with EDTA. They were also used for the determination of Cu2+ and Ni2+ ions in industrial waters by direct potentiometry.

  3. Molecular modelling of a chemodosimeter for the selective detection of As(III) ion in water

    Indian Academy of Sciences (India)

    Sairam S Mallajosyula; Usha H; Ayan Datta; Swapan K Pati

    2008-11-01

    We have modelled for the first time a chemodosimeter for As(III) detection in water. The chemodosimeter modelled is a 1,3-dithiole-2-thione derivative with an anthracene unit which has been previously described as a chemodosimeter for Hg(II) detection. Quantum chemical calculations at the DFT level have been used to describe the binding energies and selectivity of the chemodosimeter. We find that the dosimeter action is intrinsically dependent on the thiophillic affinity and the coordination sphere of the metal ion. Binding studies for a series of metal ions: Pb(II), Cd(II), Hg(II), Ni(II) and As(III) followed by an analysis of the complete reaction pathway explains the high selectivity of the dosimeter towards As(III). The dosimeter efficiency is calculated as 66% for As(III)-ion.

  4. Rapid determination of trace level copper in tea infusion samples by solid contact ion selective electrode

    Directory of Open Access Journals (Sweden)

    Aysenur Birinci

    2016-07-01

    Full Text Available A new solid contact copper selective electrode with a poly (vinyl chloride (PVC membrane consisting of o-xylylenebis(N,N-diisobutyldithiocarbamate as ionophore has been prepared. The main novelties of constructed ion selective electrode concept are the enhanced robustness, cheapness, and fastness due to the use of solid contacts. The electrode exhibits a rapid (< 10 seconds and near-Nernstian response to Cu2+ activity from 10−1 to 10−6 mol/L at the pH range of 4.0–6.0. No serious interference from common ions was found. The electrode characterizes by high potential stability, reproducibility, and full repeatability. The electrode was used as an indicator electrode in potentiometric titration of Cu(II ions with EDTA and for the direct assay of tea infusion samples by means of the calibration graph technique. The results compared favorably with those obtained by the atomic absorption spectroscopy (AAS.

  5. Ion implantation into amorphous Si layers to form carrier-selective contacts for Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Feldmann, Frank; Mueller, Ralph; Reichel, Christian; Hermle, Martin [Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, 79110, Freiburg (Germany)

    2014-09-15

    This paper reports our findings on the boron and phosphorus doping of very thin amorphous silicon layers by low energy ion implantation. These doped layers are implemented into a so-called tunnel oxide passivated contact structure for Si solar cells. They act as carrier-selective contacts and, thereby, lead to a significant reduction of the cell's recombination current. In this paper we address the influence of ion energy and ion dose in conjunction with the obligatory high-temperature anneal needed for the realization of the passivation quality of the carrier-selective contacts. The good results on the phosphorus-doped (implied V{sub oc} = 725 mV) and boron-doped passivated contacts (iV{sub oc} = 694 mV) open a promising route to a simplified interdigitated back contact (IBC) solar cell featuring passivated contacts. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. A metal ion charged mixed matrix membrane for selective adsorption of hemoglobin

    NARCIS (Netherlands)

    Tetala, K.K.R.; Skrzypek, K.; Levisson, M.; Stamatialis, D.F.

    2013-01-01

    In this work, we developed a mixed matrix membrane by incorporating 20–40 µm size iminodiacetic acid modified immobeads within porous Ethylene vinyl alcohol (EVAL) polymer matrix. The MMM were charged with copper ions for selective adsorption of bovine hemoglobin in presence of bovine serum albumin.

  7. STATE-SELECTIVE CHARGE-TRANSFER BETWEEN HE-LIKE IONS AND HE

    NARCIS (Netherlands)

    BEIJERS, JPM; HOEKSTRA, R; MORGENSTERN, R

    1994-01-01

    We report absolute, state-selective cross sections for single-electron capture by He-like ions (N5+, O6+, F7+, Ne8+) colliding on He which were determined by vuv photon-emission spectroscopy. The impact energy was varied between 0.05 and 2 keV amu(-1) The experimental data are compared with theoreti

  8. Ion Selective Ceramics for Waste Separations. Input for Annual Accomplishments Report

    Energy Technology Data Exchange (ETDEWEB)

    Spoerke, Erik David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-01

    This report discusses“Ion-Selective Ceramics for Waste Separations” which aims to develop an electrochemical approach to remove fission product waste (e.g., Cs+ ) from the LiCl-KCl molten salts used in the pyroprocessing of spent nuclear fuel.

  9. Biomimetic supercontainers for size-selective electrochemical sensing of molecular ions

    Science.gov (United States)

    Netzer, Nathan L.; Must, Indrek; Qiao, Yupu; Zhang, Shi-Li; Wang, Zhenqiang; Zhang, Zhen

    2017-01-01

    New ionophores are essential for advancing the art of selective ion sensing. Metal-organic supercontainers (MOSCs), a new family of biomimetic coordination capsules designed using sulfonylcalix[4]arenes as container precursors, are known for their tunable molecular recognition capabilities towards an array of guests. Herein, we demonstrate the use of MOSCs as a new class of size-selective ionophores dedicated to electrochemical sensing of molecular ions. Specifically, a MOSC molecule with its cavities matching the size of methylene blue (MB+), a versatile organic molecule used for bio-recognition, was incorporated into a polymeric mixed-matrix membrane and used as an ion-selective electrode. This MOSC-incorporated electrode showed a near-Nernstian potentiometric response to MB+ in the nano- to micro-molar range. The exceptional size-selectivity was also evident through contrast studies. To demonstrate the practical utility of our approach, a simulated wastewater experiment was conducted using water from the Fyris River (Sweden). It not only showed a near-Nernstian response to MB+ but also revealed a possible method for potentiometric titration of the redox indicator. Our study thus represents a new paradigm for the rational design of ionophores that can rapidly and precisely monitor molecular ions relevant to environmental, biomedical, and other related areas. PMID:28393841

  10. Vibrational-state-selected ion--molecule reaction cross sections at thermal energies

    NARCIS (Netherlands)

    Pijkeren, D. van; Boltjes, E.; Eck, J. van; Niehaus, A.

    1984-01-01</